https://www.youtube.com/watch?v=_MguVQ1Fja8&t=8 - an example of the X-Wing iMUSE soundtrack! You can hear it swap in memorable tags, literally without missing a beat.

From a musical theater composition perspective, it's almost like building around vamp sections: https://romanbenedict.com/vamp-safety-repeat/ - you build a neutral, repeatable motif that you can easily lay under unpredictably timed segments (e.g. spoken dialogue), that's primed to "explode" into a memorable melody whenever the on-stage timing calls for it!