I think its more helpful to set goals in terms of function. Saw a little woman at PT last year when she was rehabbing her knee and I was working on mine. She was almost beside herself trying to get more bend (she was already up in the 120s!) because someone had told her she HAD to get to 140(!) in order to climb stairs, and, get this, play GOLF! WTH? What part of golf requires 140?? Squatting down to get a worm's eye view of a tricky putt, maybe, but seriously 140???
Her therapist and I both told her she could find out if she could play golf better by going out and trying a few swings or playing a couple of short holes. Anyway, I'd suggest setting goals like 'walk my dogs without pain', 'ride a bike', etc.
I left PT last year with ROM in my left knee at around 120-something. At 5 weeks I could ride my horses, trim their feet, haul water for the chickens when the pipes froze, tote firewood for the stove.
Yesterday ROM in the right knee was 130 (I think that was a weasel number my therapist wanted to document, but no matter.) Call it 120-something, I could care less. I can ride my horses, trim their feet, climb stairs, walk the dogs... that's what's important.