Same. I sometimes have phases of one week where i play a lot of simracing and AC and then weeks playing other games, so the commitement for iRancing isn‘t really there. And as you said, picking a random car like a alfa romeo guilia and a random racetrack like spa and just seeing how it does, is really fun.
I try to spread things out as much as possible among the games I have. AC and EA WRC right now but I have lots of hours in DR2.0 and AMS2 as well. AC and AMS2 are the fastest to get from startup to driving in single player, so I lean towards those if I'm time constrained.