Measuring my own focus and productivity

(Not quite inspired by xkcd today, but it's topical.)

The freedom of the researchey life is a blessing and a curse, and the difference between success and failure is likely the ability to stay on target.

How can I keep myself on target? How can I even know if I'm on target?

I was inspired by Robin Barooah, who found out that he concentrated no less (and probably more) after he stopped drinking coffee. More interestingly, he quantified concentration: every 25 minutes, if he had concentrated for 25 minutes, he marks an X. Then he was able to improve it by trying something and seeing that it correlated with more concentration. (actually, by looking through his history to see that it correlated with more concentration.)

So what will I try? A few options:

1. The very rigidly scheduled day I was trying. I think this will not work; it was hard to squeeze into my day. And it was prescriptive; it made me feel guilty about chunks I missed.

2. Forget it! Just work! I think this will not work either, because my research is on a computer, so the distracting internet is always around the corner. Also, I'm unfocused enough right now that I could just read things forever and not converge.

3. Something in between: Pomodoro. I've tried this at Google with mixed success, ultimately abandoning it. But maybe it's worth another try. It's nice that it's descriptive and works in 25-minute chunks, instead of 90-minute. It's hard to find 90 unbroken minutes, and it's nice that, if something comes up and interrupts me, I could just skip this chunk, lose 25 minutes, and keep trucking.