It depends on how much I like the song/dance, it has to usually be one of my favorite songs of the year for me to watch the music show stages and fancams. Usually it’s just my ults that I watch their music show stages (although I didn’t with BTS’ On because I really don’t like the song lol) so I mainly just watch BTS, Ateez (I watch wayyyyy too many Yunho fancams lol) and Seventeen ones but if I forget one or two then that’s fine I won’t stress about it.
Oh and I’ve also watched a few of Stray Kids stages for Side Effects and Miroh because those were such bops
For YooA's solo debut Bon Voyage last yr, i watched practically (or maybe even) all her performances on music shows AND every virtual or in person/driven in concert she and Oh My Girl were in. For proof/receipts i even posted all/or almost all in a Performances/artist appreciation thread(s) during and after her promotion period, but tats cos i was (mostly still am) obsessed after how much happiness i experienced from her song/performances. Similarly with RV:IS Monster then Naughty debut/promotions. But tat was shorter n i dint post em all here, i dont think. As for my other biases last yr like Gfriend, Everglow, BP n (G)i-dle i mostly only watched (or tried to) all BP's perfs, cos the others were too overwhelmingly many, n i got sameness feeling after awhile, except maybe Mago cos it was different vibe for me.
Tldr: it depends. Some all, some less but mostly at least a few or one.