Generally speaking, there is no limit to the number of clubs an individual can join, as long as you can pass the interview or other requirements of the club.

You don't need to join many clubs (student unions). Personally, I think two or three clubs are enough. One or two school-level associations and one or two college-level associations keep in touch with schools and colleges, which is conducive to personal future development.

Students' work will affect their study more or less, but the degree of influence depends on the amount of time invested by individuals. Therefore, if you feel that you can't handle it, you should appropriately reduce your time in the department activities or quit the club directly, and keep the club that you think has the most development prospects, or the club you like. Generally speaking, if you study hard, you won't fall behind in your studies. Don't let yourself use the club or student work as an excuse.