Its amazing how much the expectance for a new album has declined through the years. I was reading the book from this Byrds album I got, and it had the original sleeve notes. It was just under a year since their debut I think, and the book was like: "These guys aren't lazy! They're just perfectionists. This album won't fail to deliver!"
If my band was ever releasing records, I'd want to do it really often. I think that with shorter gaps, you aren't expected to change as much. So like if Room On Fire or whatever had come out a few months afterward, it wouldn't have been panned as much.
Take Franz Ferdinand for example. They've been two years without anything now. When their third record comes out, not only will the hype around them have absolutely died down, but everyone will expect something magical; if we're being honest, they're never going to deliver it.