originally posted: 4:13EST, 18 jan 2013
you'd think i'd have learned this lesson by now:
never do more than one thing at a time!
here, "at a time" also includes a time period as long as the same
more on this .. but later, not now;
the sun is shining and there's work left to accomplish ..!
* = added later.
added: 14:12EST, 10 jan 2013
to explain, on friday afternoons (like yesterday) i occasionally attend a research seminar at a different but nearby university. from my campus to there, the bus trip takes about 40 minutes and buses come regularly at 20 minute intervals.
the seminar is 2 hours long and ends at 16:00. allowing time for lunch, it usually means that i write off those afternoons. so if i want to be productive at all on those fridays, then it means that the morning becomes a rather crucial worktime ..
.. and yesterday morning didn't go so well, that's all. between emails and small errands and the like, i just lost my chance to be productive. i hate it when that happens ..
i'm starting to consider forming lists of tasks that only take 1 hour to complete, like read and take notes on the proof of this one lemma from a particular article or fix all the notation from this one section of this manuscript. a list like that would be really handy because otherwise, all of those hour-long blocks of time in my schedule would be wasted ..
.. that is, "wasted" in that i start a process that takes two or more hours, like re-work the proof of a technical lemma. from experience, i rarely have the luck that it requires just an easy fix .so again: a list like that would be really useful. the problem is that maintaining that kind of list sounds like more trouble than its reward is worth.
the trouble with that kind of task is that it requires 10-15 minutes even to get into the flow of the project again, such as remembering how the lemma is used (and therefore which hypotheses can be relaxed, which ones not). even if you make a lot of progress and get the right ideas, then you still have to execute the idea.
often that involves $\LaTeX$, which always takes a lot more time than you think. there have been too many times when i knew what to do at that moment and started LaTeX'ing, only to be interrupted soon after for a seminar or class. in doing so, i'd lose that "runtime memory" that i had collected over that earlier work-hour .. so my old $\LaTeX$ becomes indecipherable crap and i'd have to start over.
i don't know. maybe i should try it anyway.
 more precisely, sometimes it is an easy fix, but you have to go through the whole argument to be sure that it will actually fix the problem (and not cause any further complications).