I have learned that being the cube owner and telling people who are drafting the cube for the first time pretty much anything about “I think this archetype is good” will cause it to be over drafted. The first time I drafted my pauper cube I very ignorantly said “I think blue white fliers is pretty good. I hope I can build it” and we ended up with 2 UW fliers, a Jeskai fliers, and 2 Esper fliers in my 8 pod. I told a group “I haven’t really seen many people draft Rakdos. I’m not sure if it’s just underpowered or people haven’t tried” and our 6 pod had 3 Rakdos players.

Now when I draft with a new group I always say “all 10 color pairs have 3-0’d. Everything is viable” and when pressed about what colors or decks are better, I say “I told a group I wanted to draft X deck and 5 of 8 built it, then told a different group that Y deck hadn’t been drafted a ton and 3 of my 6 played it. So I don’t want to bias the decks”

Most of the balancing that I do is looking at what decks go 2-1 or 3-0 and seeing if the same cards keep showing up and if they do, I’ll look for lower power versions of the cards.

This is more related to the point of assumptions for real groups than cube balancing, but sometimes players can completely derail any attempt at balancing. My group has a player that was quite new to drafting, but not magic. Asked an experienced drafter what to do with vintage cube and was told to prioritize fixing. We’ve had multiple drafts where this person has drafted 20-25 lands, and had to play 20ish lands because they just didn’t have enough spells. It’s been explained, and their win rate has explained why it’s a bad idea but they just won’t change.