For questions regarding "tag cleanup weekends" - full-throttle tag editing at the last weekend of every other month. Tag cleanup weekends are experimental at the moment.
Tag cleanup weekends are a periodic event on Super User for clearing up unwanted junk tags. While users are generally encouraged to rate limit themselves while editing (so as to avoid flooding the front page), during tag cleanup weekends, users are encouraged to edit tags and do any other necessary fixes in order to more efficiently remove and retag questions, letting the issue of front page flooding take a backstop.
Tag cleanup weekends are currently experimental, and there's no regular schedule for them at the moment. The current tentative plan for them is to have them every odd month at the last weekend of the month.