This assumes the only model is "We show up, the scenario's ready, away we go." Two weeks before my game, I present a series of three plot hooks for my Fragged Empire game; the players pick the one the want. Sometimes one of the others will lurk around for a while. But there's rarely a case of "this is what you have to engage with." Even in superhero games there are often multiple things going on at once, and you can at least backburner some of them (or fob them off on someone else).
Basically, I think your model of how games are administered is overly limited.