I adhere to the BR (at least I try very hard), although sometimes I can also play games for money or tournaments not in my BR. And this is very bad, you need to fight this, of course, if you consider poker as a way to earn money.
Ideally, you should have 100 bi per limit (the higher, the better, so that there would be more BR). Since the variance in MTT tournaments is quite large. Getting into the prize area is good, not to mention the final table.
If you consider poker to be purely entertainment, you can play any games and limits, all the same for fun