Charles, good luck on your surgery! Like you, I had no choice but surgery after a massive tear caused while lifting a hospital patient onto a stretcher. Even though I did follow-up physical therapy to the letter, I could only get to 75% extension and had to have it "manipulated" (ouch and more ouch!!!). It took me a full 9 months before I had 95% extension. A friend of mine had both Rotators done within the same year and recovered in a much shorter time, so it really depends on a lot of factors and not just age. (I had a displaced shoulder that had to be pinned, a "spur" impinging on a muscle, and a lot of scar tissue that had to be removed; whereas, my friend did not on either shoulder.)
My right shoulder has recently started to give me trouble, but like GB (wise man indeed!) it will be a cold day in the "hot place" before I visit another surgeon for that problem. One good thing that came out of my accident, was the Fish and Game department game me a "wavier" to hunt during bow season with a crossbow if I so choose.
"Kudos" to your wife for pitching in with the gardening chores! Best regards!