I ban the time sinks like Reddit and Facebook till after the work is done whenever that is. But it's unrealistic to keep working all day without browsing internet even for a little while if you're addicted to clicking links. To solve that I allow myself visits to a number of sites that are updated (with new links/stories) less often. Vice and Snapzu, for example. I let myself visit them as many times as I want for as long as I want during work. Since these are "slower" kind of sites, you'll start spending more and more time with your own work rather than chasing clicks. By the time work is done and Reddit is unlocked you'll be so exhausted you'll only spend a little time on it. After a while this breaks your addiction to Reddit. The best part is you don't have to time your work time vs leisure time.