This scene hasn’t gone on for very long, so let’s wait a bit to edit. I was in the last scene, so I shouldn’t be in this one. Thoughts like these come with good intentions but can be counterproductive. They are about being “not good but well behaved.” What they are missing is a direct observation about what a scene needs.
The heuristic that such well-behaved improvisers apply is that if one does nothing, one cannot steamroll. Steamrolling in an improv context refers to destroying what other improvisers are building and playing with by replacing them with what one feels should have been built. On the other hand, sometimes a scene has served its purpose in a few lines, and it should be edited. Kablamo! Sometimes an opportunity to play presents itself to a person who was just in the previous scene.
An alternative heuristic that can avoid steamrolling an existing scene without sacrificing one’s option to play is to makes moves from the side that do not destroy what has been built and can be played with. For instance, scene paints and playing background characters are two simple techniques that would avoid the steamrolling label but can add layers to a scene. As far as edits go, one can avoid destroying what has been built simply by paying attention to the scene. If an editor recognizes elements of a scene that could be brought back later, that simple act of mindfulness means that an edit doesn’t take away what has been built since the editor has guaranteed at least one person could bring back elements of it later.
One should note that these thoughts have a similarly misguided cousin: I’ll figure out a way to save this scene once I’m in it. While the intention might come from a pure place, thinking a scene needs to be saved could embolden one to make choices that result in steamrolling, especially if that person hasn’t thought through what they are adding. For that, I would refer the would-be savior to the alternative heuristic above, which could still serve the intended goal.