Having multiple windows open is no good. If you do the said rotation; Email-->ADTS-->SDN-->CNN-->ESPN, you have the chance of going back and checking your e-mail one more time before you quit. So, in the time it takes to check ADTS, SDN, CNN, and ESPN, the chance exists that you may have gotten an invite in that time period. If you have multiple windows open, this totally eliminates that chance of a nice, albeit rare, surprise.
Or, as an alternative, you can do what I do. Have your e-mail open and program the window to refresh q3 minutes, and if a new letter comes in, you can have your computer sing you a little song. I prefer the "A Team" themesong. Therefore, in effect, you can sit in a small room all day and wait, and you do not even have to look at the computer screen, unless you are continuously playing MS Solitaire and checking you e-mail between every game.