I was recently asked about this issue again. When I test it on my own site, what I’m finding is that when a category is configured so that all new topics and posts require approval, and the site has set their reviewable claiming setting to “required,” new posts created in the category need to be claimed before they can be reviewed, but new topics in the category cannot be claimed:
The inconsistency between the way that topics and posts are handled seems like something that should be addressed.
One reason that site’s like to use reviewable claiming is that it prevents edit conflicts when two moderators attempt to edit the same post at the same time.