Just cause of how many freaking quests involve that one damn vault.
I normally love Vaults, but that one is so boring, and I have been sent down there so many times I really freaking hate it.
There is the quest for Caesers Legion, the one for the Brotherhood of Steel, Veronica's quest, and several others.

I literally rolled my eyes whenever I get a new quest and part of it involves Vault 34.

I actually do not recall BoS quest involving 34, besides Veronica.

But, yeah, since I know what quests are involved in 34 now so I collect all of them and try to finish it in one go. I also seem to have a little bit of headache whenever I move around V34 anyway.

I only had to go there once, so far, but I completed 2 quests while I was there, so I'm lucky I guess.

There is a brotherhood quest involving that vault, you had to get stuff for their ventilation system

The three vaults needed for BoS quest were 3, 11, and 22, iirc.