"I have never met anyone who got to scratch by playing on Saturdays and Sundays and practicing for an hour a couple of times per week. I wish I had. Players who get to scratch spend more time than that. They find an hour to practice or play virtually every day."
On page 57, he adds:
"If at present you can't spare that much time, you ought to scale down your expectations until you can. If you only find three or four days a week to practice or play, you might want to think in terms of getting down to the four to seven handicap range. If you can only find two or three days a week, the best you might be able to do is around ten."
He also adds that this should all be done while using an instructor that you trust and wholeheartedly try to change your swing based on the instructor's guidance (I.e. putting this amount of time in while trying to figure things out on your own won't work).
Does your experience match up with his opinion? Mine sure does... I generally play twice per week and have one (occasionally two) practice sessions as well. Plus, I'm guilty of trying to figure things out on my own rather than sticking with an instructor. Per Rotella, that should put me in the 4 to 10 handicap range, which I am.