Well... 3h30 is a short session or the minimum time.
We don't meet for less. But its totally normal to pause at a point of the story, met again a week later and continue playing. But it all depends on what you like. How do you want to play? More like HeroQuest? Or more like no fighting at all, with a lot talking between all the Character in the world? But all doesn't matter much, you just do it like you want it.
So general games mastering? Don't panic. Play with your players not against them.