Sure... but to be honest, I rarely enjoy the entire output of most metal bands. Finding one which had consistently composed great songs is a bit of a challenge, despite the very talented interpreters and shredders from the genre. What you describe could be sort of a common disease.
Much of Black Sabbath I find hard to stomach, for instance. On the other hand, I really like a couple of their albums.
I rather find that Iron Maiden is probably one of the more consistent bands with its output, actually. You either like them or you don't, and that's a good thing by itself because it shows that, regardless of musical taste, they know their trade. Its not an easy thing to be consistent.
With Black Sabbath, I have a lot more problems because they have entire albums which are, for me, quite terrible from a song writing perspective. I don't mean a couple of songs, I mean from start to finish. If I pick one record I haven't listened to yet, I just have no idea if I'm going to like it or not.
With Quiet Riot I agree. They have records which honestly kind of suck.