I'm trying to get as many movesets with STAB moves with short cooldowns. I am guessing moves with short cooldowns may be advantages when PvP is released to allow for better dodging. At least on Pokémon that aren't my number one for that species. One example: I fast TM'd a hitmonlee from rock smash -> low kick
Also me personally I'd keep more charge TMs than fast TMs because, as we all have experienced, charge TMs don't always give the desired move first "FFFFUUUUUUUU-"