Art by Kekai KotakiEvery player starts each game with an emblem that reads:
"Players play with the top card of their libraries revealed. Players may play lands from the top card of their own libraries. Players may cast cards from the top of any library, and they may spend mana as though it were many of any color to do so."
I thought about that when writing!
I keep my color and guild sections even. For me, it's easy to keep the guilds equally represented and relatively balanced. However, the impact on draft and gameplay of going +1 or -1 card in a guild is marginal - even less so going +3 or -3 in a mono color. You could make a strong design / choice argument for doing or not doing this.
I do cheat with some cards, especially in mono-color. If I want to slot another land or colorless card in, I might see Phyrexian Metamorph in my colorless section and go "hm...you're a blue card now."