All the Inboxes and other menus that can have hundreds or thousands of results should have pages to allow for faster loading. If these inboxes had pages, they would not require the ability to load more information on a single page. By creating pages for one inbox, it could be easier to implement the same page system for other menus or inboxes. Some menus that could use this are the main inboxes as well as the Define Levels menu where similar issues have occurred.
Multiple firms are still encountering issues with the Pending inbox and To Pay when they have access to all clients at their largest firms. Recently reported by Brian Kleinman for Ground control