> I especially do this with my index fingers who will often jump from, say, Y to U directly without hitting J in between.

Oh. I don't know how common it is, but I just tried typing "yuuuuvawere" and noticed my fingers don't come back to home row unless I am done typing. They do sort of hover over it but there is no j between y and u. May be I am wrong, but touch typing doesn't teach to bring back the fingers to the home row after every letter. I learnt touch typing with some typing software which taught single letters, commonly occurring n-grams for n in (1, 3), commonly occurring words etc. So it might be my muscle memory that tells me that there is no need to go back to j if you are typing "you".

I learned to touch type with the home row thing, but I never find my fingers really going back to the home row, they just go to the next letter that needs to be typed. I guess with experience comes automatism, which in my case doesn't always involve going back to the home row after typing a letter. Or something.

Personally, I think I just have the keyboard layout more or less memorized in my head. I type about 80-100 wpm. I'll often hit the keys on the outside of the keyboard with different fingers on the fly and I dont pay attention to it. I'll put my hands on the home row, sort of, when I'm done typing something out, but my pinks usually go to shift and enter rather than 'a' and ';'