My shop floor has a permanent water stain from that same issue. It's frustrating when the simple fix makes more mess.

Remade my old pantry into a tiny painting studio last year. Sometimes the best spots are the ones you already have.

Alright, hold on. That's a pretty broad statement. A good manual calc from someone who knows what they're doing is solid, but computers are really good at running through a million variables fast. The fight isn't manual versus computer, it's about knowing when to trust the printout and when your own experience spots something the program missed. My old boss used to say the computer estimate gives you the rule, and the manual check finds the exceptions, like that one weird circuit in an old house.