It is about gains and my legs have been consistently making gains since I got here
Are you referring to definition, size or both? At you height, I think a good upper thigh measurement is probably around 27". Of course there are other variables, such as bone structure and vertical scale all of which play a part in having good symmetry.
Coach's quads look large and no doubt they are, but he's a really short man who probably has short legs, which are naturally going to look bigger.
Unlike you, my knees are still fully functional, although I did have a torn meniscus in my right knee trimmed back several years ago. When I was doing physical therapy following the surgery, the therapist had me doing individual leg presses, but no squats. There seems to be different schools of thought regarding leg presses verses squats. Same is true for lunges and leg extensions. When all is said and done, you have to find what works best for you. I'm sure you feel it when you make the wrong choice and either go too heavy or choose the wrong exercise.
Note: You are welcome to discount everything I say regarding leg size since my 77 year old legs are rails with no size at all, which is quite disappointing because when I was a teenager my quads were disproportionately large.
