Very common in the trades, or at least with everyone I worked with, we’d have periods where we had a shutdown usually lasting 2weeks but upto 3 months. We’d work 12-16 hour days 7 days a week (sometimes taking the 14th day off, sometimes not). A lot of my coworkers would go tax exempt during these shutdowns then switch back to normal afterwards.
It’s hard for me to remember all of the different formulas and remembering when to use what.