As is obvious from my record, I've stopped doing this, and figured I should do some sort of post-mortem.

1. The immediate reason I stopped when I did was traveling; it was too much of a hassle to do it while traveling, and then when I got back it was too much of a hassle to do the days when I was gone, and I made the mistake of not doing today until I had done yesterday, which led to not doing either.
2. The biggest reason I stopped was because I didn't have a good implementation / trigger. Doing it online was a mistake- yes, it was easy to make and publish the spreadsheet, but it also meant that I needed to be at a computer or on my phone. If I had been able to do it after I crawled into bed, I would have been much more likely to do it.
3. Another reason was that the list of virtues wasn't particularly compelling to me. Each of them was something I endorsed, but it wasn't clear that each one of them was something that I wanted to actively work on. For some of them, I was able to think of a way to improve along that virtue (like switching to one meal a day for temperance), but for many of them I couldn't (for order, the main new thing I could do is spend time adding new systems to arrange my things/time/etc., and tracking lapses wasn't particularly motivating in avoiding those lapses in the future).
4. Similarly, I prefer thinking in terms of systems to thinking in terms of goals (see Scott Adams on the subject).

Takeaway for me: I like the idea of daily reflection time, but if I want to record the results of my reflection I either need to schedule time for it on a computer (unlikely to work) or do it on a physical medium (likely to work, but then not as likely to get transcribed into electronic format). I like the idea of quarterly review and improvement for each virtue. I was surprised at my ability to think up ways to do various things better- I originally had thought "I've already developed X to the optimal level" for almost all of them but found that focused contemplation did come up with good ideas for several (but not all) of them. I think I got more from spending time inventing systems than spending time tracking myself, which suggests not spending the effort on tracking / not trying to spend the reflection time as tracking. I like the idea of having a dedicated aspect of myself to improve for every period of time, but I think that would be done better as ordering my list of 'lifestyle projects' and only working on one at a time (and switching to the next when I finish one) than as setting apart time to focus on things that I may or may not have a good plan of attack for.