Does what it says on the box. The only issue is that every so often it'll double up on a bunch of the links that it opens, but you can sort that out by deleting the duplicates out of the favourites folder.

Default Bookmark Folder https://addons.mozilla.org/en/firefox/addon/default-bookmark-folder/ interferes with this addon.

MY LIFESAVER!

One of alternative to Browse Periodically (https://addons.mozilla.org/en-US/firefox/addon/browse-periodically/)