Learning from Location Power Blunders: What are the big mistakes you've seen?

Hey everyone, as a camera op (currently on a spot with a V-RAPTOR XL and a stack of Forza 500 IIs), I'm trying to get a better handle on location power. I've been fortunate enough to mostly work on sets with great gaffers and DITs who handle all that, but I want to understand it more myself, especially for times we're running more independent. I've only ever tied into house power or generators, nothing too complex yet. I’m really curious about common beginner pitfalls in power planning. Looking back, what are some of the most common or critical mistakes you've seen beginners make when dealing with location power planning, specifically concerning underestimating load calculations or misunderstanding tie-in procedures? How did those mistakes manifest on set?