I'm a terrible, terrible person. [>:)]It's really too early for us to say how this is all going to work. It's still being figured out. But we can say that each episode will be self-contained -- it won't be necessary to play episode 1 before you can play episode 2. We're not talking about one big story broken up into chapters that you have to play in order. Think of it like a sitcom... Friends comes to mind. A season would have a background story (like Ross and Rachel's relationship) but each episode stands alone.
And before anyone jumps on that -- no, I'm not saying Sam & Max will be like a Friends episode.
I haven't watched that many Friends episodes (don't like the show) so apologies if this isn't what the show is like.