Wiki (and perhaps other tools; need to check) that have threaded discussions that don't show all their posts, when the default limit is reached. It is then impossible to see all the posts.
See https://sourceforge.net/p/allura/git/ci/7ffa92ac2b71a3c7247d44ef2c09bcd16f0b0375/tree/Allura/allura/templates/widgets/thread_widget.html#l6 and https://sourceforge.net/p/allura/git/ci/7ffa92ac2b71a3c7247d44ef2c09bcd16f0b0375/tree/ForgeWiki/forgewiki/wiki_main.py#l38 If paging happens on Wiki discussions using the default 25 limit, the subsequent pages won't be shown. Paging happens whether you want it to or not: https://sourceforge.net/p/allura/git/ci/7ffa92ac2b71a3c7247d44ef2c09bcd16f0b0375/tree/Allura/allura/model/discuss.py#l265
The ticket tracker does pagination for its comments. Re-use as much as possible.