When does the 'meticulous' pre-production schedule become a problem?

Hey everyone,

I'm a focus puller, currently working on a narrative short shooting with an ALEXA Mini, and it's got me thinking. You always hear about the importance of a meticulously planned pre-production schedule, call sheets down to the minute, shot lists, all of it. And for the most part, it's invaluable. It helps me prep my lenses (mostly Cooke S4s, occasionally a set of Supreme Primes if we're lucky) and generally anticipate the day.

But then on set, it inevitably goes out the window, right? A talent takes longer in makeup, the sun dips behind a cloud when you need it, a grip needs extra time rigging an amaran 150c for a fill. We end up reacting, adapting, and finding solutions on the fly. This 'reactive approach' is often praised as essential.

So here's my genuine question: At what point does that initial, detailed pre-production schedule actually stop being a helpful guide and start becoming a liability or a source of frustration on set because it's just so far removed from reality? I'm trying to wrap my head around when to hold onto it and when to just let it go.