I don't have the clock turned off, but all of the other cognitive distractions were removed long ago, particularly notifications of any sort. Sometimes I forget how distracting that stuff was because it's the first thing I do when I set up any new computer. For me, the clock isn't a distraction, but a popup for any of the million things that can happen on the intertubes is ridiculously distracting.

If I'm in focus mode, I'll also quit Adium, fire up think, and use Vitamin-R to do a pomodoro session. Works well for me, YMMV.