I had a complex rotator cuff repair 6 months ago, and I have arthritis, bursitis and tendinopathy in my other shoulder. I was on enforced lifting and training restrictions for 5 months to heal before i was allowed to begin rebuilding strength, and now must progress slowly.
I am currently on PT regimen of two days of low weight range of motion exercises, 2 days of strengthening exercises with heavier weights, 2 days of isometric range of motion and resistance exercise - all alternating and one day off. After 4 weeks I've finally figured out a routine and am beginning to feel a little progress. It is important to work the core and back at the same time. I have an excellent PT who stresses proper form to keep the shoulder properly aligned.

If you had a reverse shoulder replacement, specific PT is really important to train your muscles to take over for parts li,e the rotator cuff that are no longer functioning. And your strength may always be more limited in that arm than before injury/surgery.

Did you have PT after surgery?