Training calculators are actually pretty underrated once you start taking progression seriously. They are useful not just for estimating maxes, but also for tracking fatigue, volume, pacing, and how performance changes over time. I have been experimenting with a few myself; one is...
Usually the best approach is reducing or modifying movements that cause pain instead of stopping everything completely. Machines, neutral grips, lighter loads, slower tempo, and higher reps often help keep training going without irritating the shoulder more.
Biggest mistake I made personally...