I've seen a few topics like topic #9306 now, are there any rules/guidelines on creating subsets?

Some research:
list_of_animals is ordered quite nicely, and most tags have at least 50 posts (~110 tags).
And then there's list_of_birds, which has about 140 tags, with quite a few only having 1-2 posts. Without that list, all those subsets would have been a huge mess. (the tags may be redundant, but at least it's nicely ordered, for those that are interested).

Cats (~12k posts) - tag_group:cats:
Very little subsets;
black_cat (739 posts) - white_cat (46) and siamese_cat (6).

Dogs (~4.2k posts) - tag_group:dogs:
Has 15 different kinds of subsets (breeds), all together being 266 posts.


So, especially in case of the birds, we have a lot of subsets, but they are only rarely used.
Personally, i feel like it's fine to create subsets, but only if the creator properly adds them to the lists + a wiki article in case of strange names (kookaburra - perhaps a link back to the list would be nice as well).
As for implications/aliases, only do those when the subset reaches 25+ posts?



Related: posts that create a ton of new tags.
post #941745 (14 single-post tags)
post #674473