Adjustable but stock/pad

I posted a question on this on the Hide and got no response so Ill try it here as well.

What I am interested in learning about is the adjustable but pad. Now I own 3 rifles that have but pads that can go up, down, left right etc. What exactly am I trying to accomplish with these adjustments besides comfort? Will a certain angle seem to lay against the shoulder better? Am I trying to adjust out some of the muzzle jump?

I can find absolutely ZERO information on setting up an adjustable but pad other than videos showing how one is more adjustable than another!!

Let me guess: the video you speak of was David Tubb talking about his adjustable butt plate?

I'm guessing that because I was in the same boat.

I eventually got a Graco adjustable butt plate from Brownells and installed it on one of my Axis' Tacticool stocks. Installation was relatively painless (thanks to my 1.5HP belt grinder), but it's not adjustable in a way that's convenient. I like that you can mount pretty much any grind-to-fit recoil pad, but it's irritating to have to remove it any time you want to adjust the drop. LOP and cant adjustments were less irritating, but it was still frustrating to have to loosen and tighten two screws that my usual driver bits couldn't reach. The amount of drop adjustment is also sort of limited. I ended up installing it so most of the drop adjustment was "up", as that was the best position for prone, and I didn't have much need for it in "down".