I've always had bad shoulders. One of the reasons I was really enjoying F1 and H1 were the mobility drills. When I started at week 1 my shoulders were pain free, but clicking and popping. By week 6 my windmills were perfect, no popping. My iM work for FL1, SPL1 and HBP1 was perfect, no popping. Last week I experienced a bit of shoulder pain in the HBP and RC, so I "corkscrewed" my shoulders in like I used to do to eliminate pain. The pain went away and I kept buildiing volume.
Today I entered week 11... my shoulder popped painfully and loudly on HBP after clicking through SPL. My OTHER shoulder hurt on RC.
I'm not sure what I could have done differently.
EDIT: having thought about it for a few minutes, I guess I could have forced progress less. Meaning if I was supposed to get 15 reps and I was powering out at 12, I'd rest pause the remaining reps. Maybe I was meant to stop when the set got shaky. Maybe my joints needed a slower pace.
Also, maybe I needed more rest days. I was doing...
Mon: FL, sPL, HBP, RC
Tues: MN, SL, SLS
Wed: H1, RC
Thurs: MN, SL, SLS
Fri: FL, sPL, HBP, RC
Shoulders got hit Mon/Wed/Fri. The F1 work was never a problem, though. Twinges and pains were showing up in the SPL, HBP and RC of F1.