It would be nice if ACT! had a little summary line somewhere that simply showed how many Notes, Histories, Activites, Documents, Secondary Contacts, Relationships etc there were for the current contact. It might look like:
N5 H20 A2 O1 D0 S3 R3
You would then know whether to check that Tab.
Better yet, you could put the count right on each Tab in parentheses, following the Tab Name.