So this game has dps checks but we can't talk about our dps in game?

[thegreatonemal]

We do have that, and it is a terrible tool for the purpose of measuring your own improvement.

I know I am capable of doing my rotation as NIN (for instance) absolutely perfectly and without flaw or misstep when hitting the Stone, Sea, Sky dummies, because I don't have to do anything other than the rotation. I am in no way capable of doing the NIN rotation without missteps and mistakes when also dodging savage-level mechanics.

Then you already know what your problem is. Fix it practices parties exist. Do EXs, dungeons and the like make that rotation muscle memory.