Number of personal feeds is limited according to your membership level.

Personal feeds also have a quantity limit. Up to 500 posts can be saved in one personal feed. If you wish to add another item while you have already reached the limit, you have to delete one of the existing posts. Otherwise, you have to add posts to other personal feeds.

However, only 50 most recent (according to the posting date) posts will be visible in the feed in browser. Other posts will be archived. You can manipulate with post's date to make it visible. Or you can remove deprecated posts to free room for fresh content. All saved posts are visible in the personal feed's editor.