This formula only work if you have certain data regarding the attack speed of the skill. It is tedious work, that’s the reason maxroll website only has few skills with attacks speed breakpoint. This guy is the one produced the breakpoint in maxroll, it has a video on how to calculate it by frame analysis.
“www.youtube.com/watch?v=vFMSviKWzTE&t=552s”
There is a lot of work, but this technique work in all game. I use this to analysis the DPS of attacks combo in Monster Hunter Wild. The logic behind is you get the damage number in training room, but DPS is damage / attack animation duration. By count how many frames the attack has you can get the data which attack do more DPS.