Better racers than me may have a better answer, but my mindset is that I'm not going to chase someone around for a slipstream. If I didn't need it to catch them, then I can pass them without it too. I also think its a trap to get you out of position to make a mistake and let them get more separation. I try to respond to it only to trigger their little dance and get that person off the line that I want to use for the next turn to set up my pass. At Monza, there is a long game to this as I may not close enough to make the pass on Curva Grande, but if I do it right, I can get on their bumper out of the Lesmos to pass them before Ascari. The danger is it can compromise you from behind if someone is slipping off of you and you don't have one. I just try to live to fight another day in that situation as three or more cars swerving for a slip is almost sure to be a disaster, so I'll give up a spot...for now.