What are the differences between tag pruning on main sites and their metas?

Question

As I have learned from here and here, tags which have no questions are deleted once in 24 hours and tags which have been only used once are deleted after 6 months.

I would like to know whether such pruning is used at metas, too, and whether the frequency is different there.

Since the amount of questions at metas is much smaller than at the main sites, maybe even tag with single occurrence might be useful there.

I already know that there is one difference between the pruning on main sites and metas. The default tags which were imported from meta.SO to all metas are not deleted, even if there are no questions tagged, as I've seen here.

Answer 1

Based on the answer by @NicolasChabanovsky♦ to Single use tags are not deleted after six months if they were recreated via a rollback, it seems that single-use tags with no wiki are deleted automatically after 12 months on all Meta sites, including here on Meta SE:

It turns out that there are two different thresholds one for main sites (6 months) and another for metas including MSE (12 months). We run a script once per month which means in some cases the period might happen to be almost 7 and 13 months respectively.

The fact that the edits were rolled back is entirely incidental.

I believe tags that are not attached to any questions are deleted by the daily script even on Meta sites, but I'm not 100% sure.

You're right that the default tags, however, are not deleted even when they are not attached to any questions.