When is a Lav Truly Better Than a Boom? (Seeking On-Set Examples)

Hey everyone,

I'm a 2nd AD, and I'm really trying to get a better handle on audio considerations on set. The 'textbook' says boom is always king, and I get why. We're currently shooting a dramatic short on an ALEXA Mini with an Orbiter light setup, and we've been trying to keep booms out of tight shots, which is a constant dance.

Now, I've seen situations where the boom operator is fighting reflections, or the frame is just so dang wide that a boom pick-up is super challenging without getting into shot. My question for the more experienced sound folks (and anyone with insights!) is this: In what specific on-set scenarios have you found it truly necessary to prioritize a well-placed lavalier over a compromised boom? I'm talking about situations where the lav actually becomes the primary audio source, not just a safety. Any detailed examples would be super helpful in understanding the nuances.