Found out trace widths aren't as strict as I thought, now I'm second guessing my old mentor

I was digging through IPC standards last week and saw that a 10 mil trace can actually handle more current than I learned back in 2016, depending on the copper weight and ambient temp. My old shop lead swore by a 20 mil minimum for anything over 1 amp, but the math seems to say otherwise for short runs on 2 oz copper. Has anyone else run into conflicting advice like this, or do you stick to the old rule and just oversize everything?

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craig.john1mo ago

Take a close look at the ambient temp rating in that IPC table though. The numbers jump a lot between 10C and 40C, and most shops don't account for the heat inside a closed enclosure. Did your mentor ever talk about thermal rise, or was it purely a blanket rule for everything?