How can you manage to do that? I know some people keep a separate technical and personal blog; that does make sense. You may have other or more precise categories, but if you're not joking, 8 sounds like too much to me. Well, not too much as in "you shouldn't do it". Too much as in "wouldn't tags take care of categorization anyway?" (Once you've chosen a generically restricted enough category to begin with.) Well this assumes that tags are supported by your blogging system. But then AIUI most modern ones do.
OTOH does a use Perl;journal count as a blog? If so, then I blog too. If not, then I've given the wrong answer. But then I've given the wrong answer in any case, since I've not been writing in it anything for months, and then I've started writing in it on a daily basis (or more!) again just the last few days. So is that "often" or "infrequently"?