Don't know how helpful it is, but you can also manipulate skill levels by changing to 1 job to get a certain skill, and then going to a Nomad Moogle (Selbina, Mhaura, Kazham, Rabao etc) and changing jobs with them. The limitation is if you lower a job level, it takes every job down with it, so this is good for getting your skill reduced to subjob levels without lowering the level of WHM.

So for the sake of example, if you wanted to test like 100 healing skill, change to a job with no healing skill, and sub PLD (C skill), then set your main job level to 70, which will cap your skills. C skill with a level 35 job is 100 skill exactly. Leave the mog house as that job, and get to a nomad moogle, change jobs to whm, and you will still have 100 healing skill (although your whm will still be level 70).

It may not be that much more helpful than what you're already doing, but it may provide additional data for specific skill points after large increases in MND or VIT (because you're using a job that is twice as high a level for the same skill).