User blog comment:MisterWoodhouse/Social Activity, the 2010 Editor, and Unpausing Migrations/@comment-46665393-20201014220518/@comment-1038387-20201015201815

They used to make batches based on extensions and features that were active or inactive, like wikis with Discussions before wikis that needed to convert threads to discussions first. And wikis with more advanced Semantic MediaWiki last. But now all blockers have been resolved and there isn't really a pattern visible.