It'd be nice if engaging in combat with a training dummy popped up a button (similar to a Duty Action button) called "Reset Dummy" or something similar. Pressing this Reset Dummy button would remove both you and the dummy from combat, as well as reset all your cooldowns.

This way, you wouldn't have to waste time walking away to change classes or teleport elsewhere. You also wouldn't have to wait several minutes just to practice your openers and rotations anew if they involve long cooldowns.

The Reset Dummy functionality could also be expanded to Stone, Sky, Sea training dummies so you can try your hand at DPS checks for a particular fight repeatedly without having to exit and re-enter the area.

The only potential problem I could see with this is figuring out what to do if multiple people are hitting one dummy, but it seems to be a relatively inconsequential issue compared to the benefits of having a Reset Dummy button.