While it is true that you DO learn hitconfirming and combos when fighting the AI, what you UNLEARN by not playing in a mindgame-centric way where all you focus on is trying to analyze your foe's actions, patterns, thoughts, strengths and weaknesses etc. is so much more harmful that I can't recommend it. Now, of course for story and stuff you will play it, but that's not you trying to be good, that's just playing it to see the story, so that's fine.
I find that the mood where you're just messing around for fun and the mood where you're trying to ACTUALLY learn something and become better are very distinct so if you are just messing around it doesn't matter what you do.
If you wanna do combo and hitconfirm practice, set the training mode AI to randomly block and set up various situations and practice there. That way, your combos will improve but you will not develop the bad habits I mention. You can fix bad execution with a few hours of practice but fixing a bad mindset and fixing how you analyze the ongoings of a match if you have some type of fundamental flaw in your method of perception and analysis is much harder. Hell, just finding out you have this issue is hard since you won't know it yourself since to you what you're doing is just playing normally as best you can so you have to decipher that someone else plays differently, how they play differently, why it is better, etc. which is pretty hard.
The other way is external advice and unless a super-perceptive player plays you they won't notice it and even if they do a lot of people won't go out of their way and offer help for fear of being perceived as showoffs so avoiding having these issues form in the first place is by far the best solution. I tend to be the oppressively helpful kind so sometimes people take it the wrong way but I can't help offering advice when I see someone doing something extremely bad like not blocking on wakeup or trying to hit through invincible moves or doing punishable moves as part of blockstrings. I take the hate with a pinch of salt since I know that the hate is a big mass of salt anyways

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