As a Gen X, I think my typing speed peaked around late high school/early university? I tried to teach myself touch typing and got moderately proficient. Then I got into programming where you need to reach all of those punctuation marks. So my right hand has drifted further to the right over the years, which is better for code but suboptimal for regular text.
One thing that's really tanked for me though is writing in cursive. I used to be able to take notes in class as fast as the prof could speak. Now I can scarcely sign my own name.
So my right hand has drifted further to the right over the years,
That should literally never be the case. How do you even find your home position like that.
The quick and simple way to learn proper touch tying is simple: Use a typing tutor program. It really is all about writing random stuff without looking at your keyboard, that's all there is to it, depending on layout what you write may make more or less sense. Do that until you can actually type blindly, if you need a refresher for symbols then do that, it's worth the time investment, just for the love of everything don't look at your keyboard and don't ever rest your index anywhere but where you feel that they're in the right position. Not some feel-good "feel" but those nubs on the keys (f and j on qwerty). feel them.
You know, I'm not actually quite sure what I'm doing, but I can tell you I am not looking at the keyboard. I suppose it's similar to how I play violin? I don't look at where my hand is but it shifts to different positions depending on what makes the most sense for the pattern I'm trying to play, and yes, a different position does imply a different fingering to reach the same notes.
When learning to program, I initially tried to follow the touch typing guidelines, but they say that you should use the right pinky to reach every key towards the upper right end of the keyboard, which gets old fast given how frequently you need to access them. And just as with music, there are patterns. In programming, you may frequently need to type {}, :=, or even something like \{\}, and flailing around with the pinky is a good way to give yourself carpal tunnel. So your right hand learns to shift to hit those keys using a combination of fingers.
but they say that you should use the right pinky to reach every key towards the upper right end of the keyboard, which gets old fast given how frequently you need to access them.
I don't do that either. I hit the rightmost stuff with the ring finger, some keys are on the middle finger. The return to home position thing is still important, though, the one place to measure all distances from. Also I learned touch-typing with dvorak which may or may not have had an influence.