I've actually finished writing my thesis. I'm just putting it together now. I probably would have finished 8 weeks earlier if I worked without posting on MR, although that's just an estimate.
On the other hand, posting here probably helped me, although it's hard to measure. I found it too difficult to focus on a single task for 7 days/week, for around 40 weeks. I worked on my thesis nearly every single day, with very few days where I do nothing. In fact, I was just on vacation in Japan for 19 days, and yet I worked on my thesis (for at least 6 hours) every day except 3 days. I considered that a vacation. Pretty sweet, eh??
It wasn't the work that was the problem. It was the lack of variety.

All I did was write my thesis, which is pretty much just one single topic. I've already been working on this one project for 3 years, so imagine writing about it 24/7, over 9 months. Taking 5 university subjects and completing assignments, tests, presentations, etc, is far easier for me because the topic changes. How many hours can you spend each day watching, and focusing, on the same movie? For how many days per week? For how many weeks? Even something as leisurely as watching a movie would be difficult if you had to focus the entire time!!
You can say that I wasted my own time by posting here, but it really did keep me sane. And even though I posted here, I eventually burnt out anyway (around 2.5 months ago).

I couldn't even look at my thesis without going for a walk outside.