I'm a touch confused by this, because that's not my experience at all. You do not worry about pacing or stress as a GM. I mean, if this were a thing, and given how open these games are about how to run them, where is this in the books about how to pace the game?
Instead, you follow the fiction, the principles, and the agenda. Scores end when they end. It's not your job to bring them to a close, nor is it your job to extend them if things go really well. If you're honoring successes, you'll get to the end in a reasonable loop, absent terrible dice, and, well, that's how that rolls. PCs trauma out or are killed.