Stylistic Diversity in One Film
Even though the genre of film music allows a pretty wide variety of stylistics close to each other without feeling weird there are definitely limits to how far you can stretch the musical diversity in one film. This also includes to not constantly switch musical genres or line-ups.
A more or less fixed instrumental line-up should not just for financial reasons be maintained throughout a movie score but also to create a consistency in sound and provide a homogenous concept. However changing for instance harmonic or compositional concepts even within a cue are not much of a problem (something that would be a quite problematic thing in “serious concert music” writing).
A cue can span over late romantic string writing to impressionistic textures to atonal “horror moments” to pseudo-baroque four-part writing to electro-inspired ostinato work to minimalism and back without people finding it particularly weird as long as it feels emotionally appropriate for the scene and as longs as there is a linking element like a main theme/motif, a featured instrument or something that ties this diversity in style together.
Of course, it always helps to limit yourself to create a specific “sound” or “musical vocabulary” for each individual project as it will bring across a stronger and more homogenous conceptual idea of the music but if you need to wander off in another stylistic direction for a specific scene, that usually isn’t that much of a problem. However never get to a point where your music could be replaced by picking more or less random cues from a music library because there is just so much diversity that practically no connection can be noticed anymore.