It’s kind of fun to look at the graph of weekly traffic at LessonIndex.com since August, viewed as a proxy for “lesson planning activity.”
You can see quite clearly what happened during the holiday season: there’s a sharp drop for Thanksgiving, and a bigger plunge during the Christmas/New Year’s break. (Note that the baseline for this graph is not zero.)
Update May 24: I’ve replaced the earlier graph with one that extends from September through mid-May. You can see “spring break” and the overall decline as the end of the school year approaches.