Well put, Wiseone. Cat could have played a garden hose and still sound good. He obviously put in the time and continued to practice diligently.
I heard Doc last week and at 85 he still is a monster. Doc is well known for his dedicated practice routine, lot's of long tones, soft playing slurs, etc. It's boring as hell but it's also the secret. The only trick or secret is patience. Cat obviously knew that as Doc still does.