When do hybrid camera overheating limitations really matter?

Hey everyone, I'm a Key Grip, typically working with gear like an ALEXA Mini or a VENICE 2 on narrative stuff. I keep hearing about hybrid cameras (like a Canon R5 C or a Sony FX3) potentially overheating during long takes. What are the actual, real-world shooting scenarios where this becomes a critical problem where you just couldn't get by without a dedicated cinema camera? I'm talking about situations where you absolutely need an ALEXA 35, or even an FX9, because the hybrid would just crap out. I'm helping a buddy spec out a small commercial project, and we're trying to figure out if we actually need to rent something beefier. Thanks!