A Poll, If You Will.

I'm having a hard time wrapping my mind around something, and I'm hoping to gain some insight from my lovely readers. In my business, e-mail correspondence is imperative to a successful working relationship. Similarly to "real" life, if someone doesn't respond to you in a reasonable amount of time, it's obvious you're being ignored. Now, I'm not not saying I've never taken a few hours to respond to an e-mail, but that's probably the maximum. Unless I'm ignoring you, you get a response. The whole point of e-mail is to engage in a quick conversation. If I wanted a conversation to drag on and keep missing someone, I'd make a phone call. I guess my issue is this, if someone who you work with/for e-mails you, wouldn't you agree that it's common courtesy to respond? I'm curious to know how often you, as an professional/friend/human being A. check your e-mail, and B. How quickly you respond?