It lets you limit the number of minutes you can read sites (and importantly links from thoses sites). I give myself 10 minutes per day until 9pm at night.
My router at home blocks Reddit and HN except from 5-7pm and 11:45-midnight (and all day Saturday). Worked amazingly well to cut back the addiction. Now if I could just get HTTPS blocking to work on FB and Twitter.
I don't know why but I find myself opening new tabs without thinking about it. On Facebook? Ctrl+T, fa, down arrow, enter. Why? Who knows, I was already there... That's when I noticed that I have some major problems.
You can lock yourself out easily with noprocrast and minaway set to a week or two (say 60 x 24 x 10). At least one prominent HN'er claims to have done this when needing a break.
Happy to have been of assistance; please send the $250 to GiveWell. ;-)
That's generally how long I need to break an addiction