Motivated vs. Unmotivated Lighting: When to break the rules?

Hey everyone,

I'm prepping for a short film next month, mostly run-and-gun with my ALEXA Mini, and it’s got me thinking a lot about lighting. I’ve always been taught the 'motivated lighting' principle, light sources should make sense within the scene, like in Sicario, which nails that realism. We're using a couple of PavoTube II 30Xs and an LS 1200d Pro for our key and fill, aiming for that natural look.

But I'm wondering, in your experience, when does sticking strictly to motivated lighting actually hinder a scene? Are there times when cheating with an unmotivated light source, just for narrative clarity or emotional punch, is the better call? For example, adding a subtle Forza 500 II off-camera to emphasize a character's isolation, even if there's no logical source for it in the frame. I’ve experimented with it on some smaller docs, but it always feels a bit like breaking a cardinal rule.

When do you consciously decide to ditch realism for impact?