According to a quick google, you can only have up to three of the same cards in a Yu-Gi-Oh deck. So you can't keep the ratios the same.
I don't play Yu-Gi-Oh, but I play Magic, and it's similar there, but you can have up to four of any card.
I imagine most trading card games are like this, otherwise you could just make a deck of only the most OP card or something. Not exactly fun to build, or play, or play against.