There is never enough metal.
All things in moderation!
I prefer having a varied taste and giving everything a shot cause you never know what awesome song or band you would have never found otherwise. Plus you learn a whole lot more about what bands are influenced by what other bands, where people sample sounds and melodies from, and just music culture overall by having a varied taste. Metal's fine and all, but I never sit and listen to a particular genre back to back to back.
This morning I was goofing around with Ska and listening to random related songs and artists, but now I've moved on and and playing Blues Rock / Hard Rock.
Here, have some guitar-y goodnes courtesy of The Yardbirds
Metal is the only genre that I can listen to exclusively for days upon end. I listen to many other genres (dubstep, pop-punk, ambient, post-rock, hard rock, prog rock, 80s pop, select modern pop, metalcore, some select jazz and blues, etc) but metal is so varied (there are such a wide spectrum of different styles in metal; technical metal, brutal metal, minimalist and atmospheric metal, sloppy 80s metal with punk attitude, etc), that there is literally enough metal to last a person for months upon end, should they decide to listen to it exclusively.
As I said, I listen to many other genres, I know music history and how each band influences the next from the 1930s onward, but there are NO genres that I will EVER love and adore, and will be able to appreciate in the same way, and be able to listen to exclusively for days, but metal.