I try to restrict my tags to a relatively small number of significant themes. (They can get revised if a particular theme explodes all over the place, as with my "reviews" tags which got a thorough overhaul at one point.) If I thought I were going to blog a great deal about the cloak-weaving project, it would be worth creating a specific tag (at which point I'd have the annoying task of going back to identify previous posts that should get it).