I used to have less patterns in my practicing when I first got really into practicing my AT's, just kinda picking the game up in training/infinite time with lv 1 mode for 30-90 minutes at a time and working on SHL timings/heights, wavedashes, SHFFLs etc, depending on how much inspiration I had at the moment. As the basics got more under control, the practice time/regime got more structured as I begun to focus more on more specific maneuvers like waveshining and LHDL. When last semester kicked off, I was practicing 1-2 hours almost everyday working on whatever came to mind that I could improve, like my understanding of individual character physics in context of combos, shineaerials, making my basics more frame perfect and clean (such as L-cancel timings with delayed aerials/against shielding opponents vs straight up SHFFLs), and basically attempting to refine every little nuance that I could hypothesize.
I'm not done, by any means, but I feel a little more in control of my tech skill on a more advanced level now, so my weekly average practice time may be less consistent now, but I'm not sure...guess I'll have to see if I have any more significant projects or something that I want to undertake. Although learning double shines and attempting multishining in general afterwards will likely prove me wrong on the declining practice time deal...especially when putting it in context with shield lag and waveshining and such
I feel like practice time is largely dependant on choice of main, though. A spacie player can easily find enough material to fill an hour of time in training over long periods of time, whereas a Puff player, for example, might just spend 20-30 minutes every now and then. I don't have much case-specific evidence to back that claim up, though...I just hear my Puff friend telling me about needing to practice his enormous tech skill all the time
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I also just may inherently have a more analytical and systematic approach to practicing tech skill, though, being a music major on bassoon (which is innately a less intuitive instrument than most) at my college; I try to apply the concepts of breaking things down into smaller chunks/slowing them down (not necessarily in training mode in smash, though, just not necessarily TAS training drills or anything like that) and repiecing them together to my tech skill practice. I know doing that in combination with training mode is really helping me with double shines right now, really analyzing all of the mechanics of every last part of the double shine and mastering the theory as well as the muscle memory.
EDIT: Oh, and in general, one should practice alone 20-30 minutes a couple of times a week to keep all of their tech skill fresh, sharp, and not rusty...especially if he or she plays a spacie. Things just get too rusty too fast for spacies...at least in my experience.