I wouldn't know about CCSF nowadaze. I haven't been there since '78. Then, the full top 6 singles, 2 of them play doubles, and 2 other doubles teams comprising non singles players. Coach Phelan was the boss, and weights, running, diet, plus countless drills with other players was the daily call, easily two sessions, 5 days a week.
StanleyWoo and DexterLee were my practice partners before they joined CCSF, by '78, they were getting better than me in strokes and tactics. Doesn't mean they did better in tournaments, as that's something else. Dexter won ChineseNationals, while Stanley and I regularly went 4 rounds. We all entered OpenTourneys and local Q, the TransAM, I got the furthest because I'm lefty and unconventional.;
But I never practiced, never drilled, and hence dropped out of the game by '79.