When does strictly motivated lighting become a detriment?

Hey folks,

I'm prepping for a short film, trying to really nail the visual style. I keep coming back to how much praise Sicario's 'motivated lighting' gets, and for good reason, it looks incredible. The idea of every light source having a plausible reason for being there (windows, practicals, etc.) makes total sense on paper, and the realism it creates is undeniable.

But I’m wondering, from a practical standpoint, when does this textbook approach not work? I’ve found myself wrestling with a scene in a dim diner with my ALEXA Mini LF, trying to make the existing practicals look good with my M18, and sometimes it just feels... flat, or like I'm fighting against what the scene needs emotionally. I’m thinking about introducing a SkyPanel S60-C that doesn’t have an obvious source, just to lift the actor's face and add some punch.

When do you guys decide it’s better to 'cheat' with unmotivated light for narrative clarity or emotional impact, even if it breaks the 'realism' rule? Or when have you seen strictly motivated light actually detract from a scene?

Thanks for any insights.