Thank you, Abra and WVWoman, for the kind words. Nothing like tea and sympathy -- I usually have a cuppa -- well, something -- while solving.
To clarify, I was flat on my back for 12 hours, then spent a sleepless night by the computer, and it had just turned the 1st of February. Solving focuses the mind, an excellent diversion.
btw, changing the subject, Nanrich wrote an excellent summary of techniques for solving these puzzles quickly. It is a matter of "seeing" and recognizing patterns at a glance. But while I can do that with maybe 85% -- improving slowly with practice -- she solves every single one at warp speed. Awesome.
Even if I had all day, almost certainly there's a few I'd miss. That, coupled with lack of patience, means I go for speed and leave many unsolved. The quick and the dead, that's my current strategy -- if it doesn't come clear in 30 seconds, basically, it's history till next time.