I compete in IBS Score Competition with a 6 BR. As with any firearm competition there are a lot of steps involved in the loading and reloading process. I don't really "hate" any of them but, do dislike some more than others.
That said if I had to pick one that I dread the most (I guess), it is new brass prep. To preload for a 3 yardage Match, I have about195 cases. So starting with 200 new ones it takes F-O-R-E-V-E-R to get them neck turned, prepped, fire-formed, cleaned, resized, trimmed, etc., etc., and ready for Match usage.
The good news is that with minimum sizing along with annealing, a set will last a full season, sometimes two, so the whole new brass thing is infrequent. Yea!
SJ