Personally I’d say about 40 sessions is a very reasonable assumption. One year of weekly play should be an achievable goal.
And yes, the point about other systems is very true. I’ve played lots of games which have a tighter focus than DnD.
Its not only that but D&D style games tend to gate a lot of options behind level. Given they don't have the zero-to-hero bias, that's much less true for a lot of ones outside the class/level paradigm.
True. I can’t really see an open ended Cthulhu game. Your characters are going to come to a bad end. The only question is how bad and when.
Or an open ended Dread game would require a honking huge Jenga tower.![]()