I just updated tags on a bunch of old posts. I do that once in a while, since Blogger makes it easy to do. If I realize that all the posts mentioning “Windows” should be tagged “Windows”, it’s easy to do a search, select all, then apply the tag.
The weird side-effect of that is that if you look at this feed, a bunch of old posts are bubbling to the top now. That’s OK though. I don’t think anybody looks at that feed.