The lead was right about the chip load being too low, but "leave it alone the whole pass" is the part I'd push back on. Sound is still info, it just isn't the thing you adjust by. If a cut starts sounding off mid pass, the move is to stop the feed, check your insert and your chip shape, then figure out if it's wear, a bad setup, or the material acting up. Running a chipped insert to the end of the pass because the chart said so just wrecks the part and the holder. Charts are a starting point, not a law.

That water damaged box story hurts my soul.

22 years and three shops closing roller work is real, sure, but "dying" gets thrown around a lot in the trades. Every old hand I've met swears their way is the last real way, yet folks still roll tubes in refineries and condensers all over. Honestly 9 jobs is a small sample, and plenty of that weld work still needs someone who can roll when the spec calls for it.