I think most authors envision agents sitting at their computers, drinking coffee and constantly hitting the "Get new mail" button while waiting for one query to show up.
This came to me in an email recently, and thank goodness I'd attached the coffee IV drip rather than having anything actually in my mouth or it would have been all over the keyboard.
The advent of electronic queries means that unlike the paper mail, queries arrive around the clock. When I first started taking queries by email this drove me nuts. I treated it like regular email--I answered it when I got it. That was clearly not going to work at all so I figured out how to work the "redirect to folder" function on my mail program. Now when something comes in to the right address, it goes directly to the query folder. When something comes in to the wrong address, I just move it over manually.
I read queries in batches, twice a day, morning and evening. It takes about 30 minutes total to read 20-40 daily.
The rest of the time of course I'm dreaming up new hoops for you all to jump through.