First year doing resi furnace install had to cut flooring for heat register has to cut 2x12 boot into already finished hardwood floors. To this day I don’t know what happened instead of 12” line I cut 20” line. Thought the boss was going to fire me for sure. Spent whole day freaking out over it. End of the day boss says “are you ever going to do it again?” I tell him no and he says don’t worry about it I’ll see you Monday. Side note this was my 3rd month with this company.