I was trying to boil my thoughts down to a brief statement on my lunch break. I don't really see much of what you pointed out as in conflict with what I'm thinking.

Incidentally I hadn't forgotten the fact that some channelers start out at an initially higher strength value, or even that theoretically someone could channel at above the necessary level for the final test on their very first try. However, I abstracted that from the thought process in my post for both brevity and because we all know that there is a certain experience level necessary in addition to power level.

The height growth analogy does seem like it would work, except that it leaves out one thing. It doesn't address the fact that we are specifically told frequency of channeling, duration of channeling, and total magnitude of channeling all play a factor in growth rate. In fact an abnormal increase in any one of those factors can cause "forcing" or growing in large, non-linear spurts...a "growth spurt" under your height analogy. In my thought process I was equating "tower training" specifically to "number, length, duration, and magnitude" of one power lessons in a given set of time. Which would be roughly the same, though not perfectly identical, for the vast majority of tower initiates.