I watched it in two sittings, Klyd. Four and a half, then five. In each sitting I had a few mini-breaks at appropriate points. Because it's a succession of "talking heads" (but so much more than that; better seen than read about), I actually think it becomes more compelling the longer you sit and watch it. Breaks can become detrimental to films with this sort of rhythm. Time itself (along with repetition) becomes part of its meaning and power.