If you don't have time to do something that's literally an hour into the game I'm surprised you had time to install it.
Unlocking the tracks is not a matter of time, in that case it's skill. I know there are some blisteringly fast players out there, but believe it or not, it's almost certainly not within everyone's ability to score those gold medals required to unlock the Nordschleife 24h track. Just as it's completely unlikely I'm ever going to score gold on all the license tests, even if I tried them all a hundred times.
And it's not necessarily just a matter of practice. Even in "hardcore" sim racers like iRacing (which I've been playing on and off myself for a year) - where everyone is playing with a steering wheel and have enough of an interest in a hardcore sim to pay a monthly subscription plus potentially several hundred Dollars worth of content - there's a vast gap in skill level and thus lap times between the fast and slow drivers.
I fall into the latter group, and while I certainly believe I have room for improvement, some people are simply more naturally talented.
I haven't run the Nordschleife special events enough times to gauge whether the gold lap/sector times are likely to be truly difficult for a slow but consistent driver, but they certainly seem out of reach for now.