The biggest reason Imola is struggling to produce good F1 races is that awful main Isn't Straight. On a wide circuit, the kinks in the straights don't often make a difference, but there are plenty of examples where having a long section between braking points drawn freehand is detrimental in many ways to good racing.
For starters, an arrow straight Straight looks interesting from head-on camera shots, something which can be achieved somewhere like Shanghai, but needs three or so cameras to follow action at Imola. These kinks are designed in a way that first goes right past the Pitlane (the starting grid feels like it's in the wrong place but that's a different issue), before two left kinks before a left-hand bend. The first of these kinks is at terminal velocity and has directly caused massive accidents at Imola since it came back to the F1 calendar, including the Russell/Bottas collision in 2021 and the F2 disaster this year. The second of these kinks left in the braking point naturally squeezes the racing line, making defending a line on the inside super-easy as the car will naturally drift wide and narrow the width of track an attacking car can have. Couple this with the nature of the following chicane being medium-speed and having only one real line and clunky kerbs and side-by-side action cannot exist further than turn 4.
How can the main straight have 3 official corners in it?
The track may have only one DRS zone, but that's not really an issue as plenty of other circuits are like this. Passing is possible at Losail, Mugello and Suzuka too, but that is helped by having a good main straight to allow the passing on. Losail is perhaps the best analogue for comparison to Imola. It is also a varied circuit with short straights, high-speed turns everywhere and only one main straight. In its two F1 races, the order changed a bit even if the passing was mostly only done at Turn 1, and sometimes did make it to Turn 4. Imola has a fine, historic layout and the isn't straight not having the Variante Bassa chicanes of the 2000's is definitely an improvement, but Imola had always (at least since the changes after 1994) been a track like Monaco and Hungary where passing was going to be difficult, as shown by the 2005 San Marino GP. Where Hungary seems to have had a renaissance in the Hybrid era to being quite regularly an incredible circuit for F1 wheel-to-wheel action, it sadly never spread to Imola.
Screw it, time to turn this post into a rant, essay about Isn't straights in Motorsport.
There a multiple different types of "Isn't Straight". By this I am defining a straight as starting from the point where the car has left the corners where the car was first flat out. So for example, the Hangar Straight at Silverstone starts after Chapel, as it is part of the section of corners preceding it. The end is the apex of the first major corner where either braking has happened, or you would naturally assume DRS wouldn't be used. This allows me to rule out classing Luffield to Becketts as one straight as Copse despite being flat-out in an F1 car, is definitely a corner. Turn 1 at Suzuka also counts as the end of the straight.
The best kind of isn't straight, and one which could be argued works far better than a conventional straight line, is one where the straight curves one way, and the following corner turns in the opposite direction. This is still further split into two types.
Curve into Opposite corner:
Hockenheimring T4-6, Knockhill T7-9, Montreal T14-1, COTA T11-12, Long Beach T13-T2, Sochi T2-4
This Straight is defined by one with a pronounced direction change down the length of the straight, with the first corner after being to the left if the straight curves right, and vice versa. The slight curve makes a singular line of least distance viable, but one which still requires a bit of steering lock, scrubbing a small bit of speed off the car. As they get around the corner, they will naturally be on the wrong side of the track for the racing line and have to take a longer line to get to the ideal. This makes the ideal line a longer distance, and thus the inside line for the corner becomes a lot easier to pass into. Hockenheim especially is the master track of this, and the modern layout has proven itself over so many years to be one of the top 5 circuits for wheel-to-wheel racing in any category.
Corner into Opposite corner:
Istanbul T10-12, Nurburgring T11-13, Hockenheim T6-8, Singapore T5-7, Suzuka T14-16
The alternative to this is to put a single but significant direction change halfway down the straight. This can be an easier corner like the kink under the bridge at Singapore or something more dramatic like 130R at Suzuka. If this corner is one which cars can easily take flat-out, then it helps make it a slipstream boosted zone or a corner drivers can take side-by-side. This has the same effect of making drivers choose which side to defend with. Do they take the faster racing line which means taking a longer line or defend the inside and deal with the consequences of giving an attacking car the racing line? The fact Hockenheim has one of these Isn't Straight configurations directly after the previous isn't a coincidence and is a significant reason for the layout's success.
So curving into the opposite direction is good, but how does it work the other way around?
Curve into Same corner:
Abu Dhabi T7-9, Nurburgring T15-1, Interlagos T12-1, Melbourne T2-3, Brands Hatch T9-1
When the curve before is the same direction as the one following, the curve feeds perfectly into the racing line, thus making passes slightly less likely and mostly bolder. Whereas Abu Dhabi, Interlagos and Melbourne in these examples have the curve done early, the others have a small kink before the braking point, where the car on the inside can quite easily turn a straight braking point on the inside to a perfectly reasonable middle-of-the-road position, squeezing out the car on the outside. These corners usually have the larger crashes in wheel-to-wheel racing at them compared to the others. Whereas a regular straight may get plenty of collisions and the opposite turns have plenty of divebomb related accidents, the wheel-tangling of moving braking zones means there are significantly larger crashes at for example Turn 3 at Albert Park than anywhere else on the track with plenty of passing spots.
Corner into Same corner:
Sochi T18-T2, Magny-Cours T3-5, Laguna Seca T11-T2, Virginia IR T17-T1
When the kink in the straight is a more pronounced corner, it produces a more rigid racing line, which works spectacularly for when the next corner goes the opposite direction, but fails when it makes both cars in a battle end up on the correct line for the next point. It basically shops the straight up into two sections, requiring the following car to be side-by-side by that corner to force one or the other off the ideal line. This one in particular makes divebombs or late moves much harder as momentum down the straight can be disrupted for the following car badly through these corners.
Chicane Straights:
Red Bull Ring T1-3, Red Bull Ring T3-4, Abu Dhabi T5-6, Mugello T15-1, Bathurst T17-20, Sepang T2-4
A chicane straight has two kinks in opposite directions along it. This can range from something like the Conrod Straight at Bathurst, which works just like a "Corner into Opposite corner", to something as disgusting as the silly lane change on the straight at Abu Dhabi built because the Grandstands were too high and the track wouldn't have been visible without the lane change. These double direction changes often mean there is one line which crosses the width of the track and a following car has to pick a side and force itself to be noticed. This works somewhere like the Red Bull Ring, where the T1 and T3 corners respectively are fantastic for getting a following car into a position to pass down the next straights, and the kinks in the straights allow for divebombs at T3 and the passing driver getting into the position to go around the outside of T4. The chicanes are easier to defend on if the following driver isn't able to get an overlap and they often just look messy on TV.
Wobbly start of a straight:
Baku T16-T1, Spa T1-T6, Indianapolis Road Course T4-7
Before bringing up the proper Wobbly straights (the worst of all), it is worth pointing out that long flat-out sections can still be passing zones IF the corners are done early. Baku and Spa have the two longest sections of flat-out on the F1 calendar and get their corners out the way earlier, while the chicane at Indy isn't quite flat-out, it also fits here as a "mistake generator" section before a long straight which is perfect for making a driver under pressure lose momentum before a proper passing point.
Wobbly Straights:
Imola T18-2, Sochi T10-13, Melbourne T6-9, Valencia Street Circuit - All of it, Miami T8-T11, Jeddah T17-22, Nurburgring Nordschleife - Döttinger Höhe
As mentioned in the Imola rant above, the wobbly straight is the worst. This abomination has 3 or more direction changes in multiple directions. Whereas something like Interlagos has a big continuous curve made up of a few apexes and feels natural, a selection of apexes in multiple directions just brings in multiple issues. For one (as most prominently publicised at Jeddah), reducing sight lines to drivers at 200mph is a terrible idea and each kink becomes an elevated chance for massive crashes from drivers unable to keep a defined lane when side-by-side. These kind of straights often exist somewhere where it is forced by geography or the streets, and thus these straights can be very narrow, exemplifying the reduced sightlines issue. The straights need more cameras, more marshals flag posts and reduced view for spectators in the grandstands of the battles down the straight preceding the big corner they are sat at. If you ever design a track and have a blank canvas, for everyone's sake please do not ever make your straight wobbly.
Thank you for coming to my rant about straights on race tracks that aren't straight. Also do not ever call a section of a race track a "Straightaway".