Find a way to do that at least 2 times a week at least couple hours each time. Just to maintain what you have learned. If you want to get better you need more, obviously.I guess once a month on average.
Dancing is a physical skill as well which you need to reinforce regularly to keep up. Also you need a lot of repetitions to remember what you learned. And they need to be spaced close enough at first. (Look up spaced repetition)
If your teacher didn't encourage you to do that, then of course change teacher. But teachers I've met have been explicit that students should go out and dance.
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