The most imp thing that makes you a fan is the music so if you listen to the music you are a fan. It isn’t possible to keep up with all the groups and fandoms if you stan a lot of groups but as long as you follow comebacks it’s all good! Most of the groups you’ve mentioned produce a lot of content so I would suggest that you either follow some fan accounts that update regularly.

I personally love NCT content but I also follow groups like svt, txt, got7, itzy and blackpink so I watch only the NCT daily/WayV content. For the other three groups I only keep up with the comebacks / check updates on my twitter tl and Reddit. My ult group is SHINee and they don’t produce a lot of content so that works well for me lol and I also love EXO and they’re on hiatus too (plus they’ve never produced NCT level content anyway). Remember music is what makes you a fan!