I was a student of the WTA (under GM Son) from 1999 to 2016, and currently practice with a group that continues to practice the same forms, and fighting styles taught by GM. As far as "Speed", it has always been the last of our forms foundations. As per every instructor I have practiced with (including the GM), it is Balance, Power, Focus, Control, and (then) Speed. Sacrificing Balance, Power, Focus, or Control for speed is not (and never was) an option. If a student (or even an instructor) form is getting sloopy because they are trying to gain speed, they are told to slow down.