It’s remarkable how many Ph.D.s never manage the simple mathematics involved in reading a conference paper. Notorious Ph.D. has some great unsolicited advice on the topic at her blog.
One basic rule bears repeating: It takes at least 2 minutes to read a double-spaced typescript page. So if you have only 20 minutes in which to read, there’s no excuse for trying to read a paper of more than 10 pages — and that’s if you don’t care to allow any time for Q&A.
A remark by the Quaker preacher John Woolman comes to mind: “Where people are gathered from far, … it behooves all to be cautious how they detain a meeting.… In 300 minutes are 5 hours, and he that improperly detains three hundred people one minute in a meeting, besides other evils that attend it, does an injury like that of imprisoning one man 5 hours without cause.”