Oh, this question is for me. I also switched from singletapping to full-alternating in february. I learned to start triples, streams, doubles, etc. with different fingers depending on which came next. But after a month or so, I noticed that I had reverted to always starting triples, streams, etc. with my pointer finger.
This happens because our brains are slightly better at doing triples etc. starting with the pointer finger, and the brain will automatically choose to do the finger movements that are best at producing rewards (i.e. hitting triples correctly is what we want, so it produces dopamine) even when we aren't paying attention.
Most top players who alternate do semi-alternate. Which means that they'll play XZX XZX XZX (semi-alternating) instead of XZX ZXZ XZX (full-alternating) on three consecutive triples. While that works fine, I think full-alternating works better, and I explained some of the reasons why
here. The main argument is simply: after having tried both, full-alternating
feels more smooth, feels less clunky, feels less like stuttering through complex tapping patterns.
I started learning full-alternating again about a week ago, forcing myself to the XZX ZXZ XZX patterns. It was a really big reset of my skill-level, and even made me worse at aim for a while. If you want to start ful-alternating again, I
highly recommend using
this AutoHotkey program to force your fingers to use the correct patterns (I
asked peppy, and he says it's fine). At the start, I just struggled through
this map (Shiki - Angelic Layer) a bunch of times (wasn't fun) until I was competent enough to practice on fun maps.
EDIT: If you want, you can poke me when I'm online and we can play the slow versions of that Angelic Layer map a bunch of times together in multi (I played the slow versions on half-time at first). Even playing them halftime is good practice for me, since I'm really bad at accuracy and low bpm. : )