When do budget photo lenses become a false economy on set?

Hey everyone, I'm trying to figure out the real-world breaking point for using adapted photo lenses. I'm gaffing a short film next month, shooting on an ALEXA Mini LF, and the DP is considering a set of rehoused Sigma Art primes to save a chunk of the budget. My previous gig, we used proper Cooke S7/i's on a V-RAPTOR, and the workflow was seamless. I'm wondering at what point the initial cost savings of lenses like the Sigmas, or even some rehoused Canon FDs, start to get eaten up by headaches in post or limitations on set that I might not be anticipating from a gaffing perspective. Are there specific scenarios where that 'budget-friendly' choice just bites you later? For those who've gone this route, when did it become more trouble than it was worth?