It’s hard for me to remember all of the different formulas and remembering when to use what.

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.