It's all in where you live I guess. Here in Arizona almost everyone feeds straight alfalfa. Grass hay is very expensive.
So I am feeding almost straight alfalfa with just a flake of bermuda here and there for my youngster to try to get him a more balanced diet. I have always heard that if you can get a 50/50 mix of grass to alfalfa that would be close to perfect.
It's kind of funny how what is "normal" depends so highly on where you live. I would love to find a quality alfalfa mix without paying a king's ransom for it. It's the grass that is expensive out west!