Theatre is such a weird, ephemeral thing. even if you are in a production where you are supposed to do the same thing night after night, it is different every single time. The audience is different, your mood is different, things happen with teeny shifts in different timing; changing everything slightly, or even a lot. That is the magic of live performance.
It is especially obvious when you are improvising. Here you don’t know what you are going to do until it is done, and the idea is that it can never be recreated. It exists purely and powerfully in that moment, and then it survives only in memory. That is what distinguishes all the moments and scenes and evenings of improv. Are they memorable?