Are you linking the pictures to an outside directory or allowing FTM to copy the photos to its own directory?
I do not have much media attached to my family tree but those that I do, I have the linked to the directory where they originally resided.
All of my data, pictures, census, document, etc are maintained in a set directory structure. It basically consist of the families of the four grandparents of my wife and I. In the primary family subdirectories are subdirectories for all of the maternal sides of that family All primary, and maternal family subdirectories have at least these subdirectories.
--Documents images of any family document
--Census: Images of all appropriate census reports
--Burials: Tombstone images and cemetery maps.
--Pictures: Pictures of the family
--Residences: Pictures of family homes or farms
There may be more subdirectory as needed.
In this way if I wish to add a picture of person A to FTM, I direct FTM to the appropriate subdirectory in MY directory structure. If I wish to look at a picture of Person A I open the appropriate sub family directory open Pictures and they he is.