All things being equal, depth trumps power—
Gotta say, depth over power.
Right that you are logical about your progression, but my comments are about the age old argument quoted above.
Yes, I realize you go on to describe how you see the progression of a player in a very logical progression that does have some merit....but my point is that I'm convinced that the quote above is not the best starting point for your progression. I realize it is the most accepted starting point and has been established advice for many years, so you have that advantage. What I'm saying is that "depth over Pace" is a logical fallacy that when examined, doesn't hold water. It requires so many braces to hold it up.
For instance, the question assumes you have the option. It assumes you can do either one and which will be better on avg...... Depth will rarely EVER trump Power. If you are comparing equal skill with each, then power is nearly always the better choice.
Also, What is depth? When I bring depth up as "the back 3-5 ft of the court" here on tt, many will argue saying good depth is merely past the svc line. Ok, so if that is true, then tell me you
rather hit a soft shot to 1 ft past the svc line instead of a 75mph rip to the same bounce point (given you understand why you can't hardly hit 75mph inside the svc line except in special situations). If you think hitting past the svc line is solid depth, then this whole question goes out the window, because you should realize that even moderate pace is going to achieve this level of depth on the reg.
So Imo the much more accurate starting point for this logical progression is, " Depth when you can't produce Power". If you don't have the skill or you are in a poor position to create or use your power, then sure, good depth can help. As to the progression, hitting higher due to low power to produce more depth can be a good tactic, but wouldn't normally be better than good power and Imo actually will delay developing the skill of more power. As you learn to groove your stroke with a higher trajectory to add depth, this habit runs counter to a trajectory that will be more accommodating to developing skills for hitting with power. Hitting higher for depth will develop habits of opening the racket face, swinging more "low to high" and modulating power for control. If the goal is to develop a strong and powerful game, then using a trajectory, racket face angle and swing plane that will give success with a powerful swing is the more productive path. Imo this is why some of the greats have suggested to hit it hard first, then try to learn how to control it later. Oddly I don't buy into the hit it hard, control it later mantra either