Ficus Benjamina (Weeping Fig) losing leafs ?

Ficus Benjamina does this quite regularly. Don't worry, leaves grow back. We have about ten of them, some are 2 or more metres high and more than a metre wide and they have almost all, without exception, lost most of their leaves at some point or other.

I've never worked out why it happens. People say they don't like being moved but a couple of them have regularly travelled with my daughter when she has moved digs and it doesn't seem to bother them at all.

I'm very careless about watering, for them it's often deluge or drought and that doesn't bother them either.....

Thank you for your reply i feel a bit better now knowing that the leafs grow back and that it happens to other people as well lol, ive moved it to another part of the living room and the leaf drop has slowed down and it still looks healthy !! so maybe it didn't like where it was ? who knows !! but i do feel that they are a sensitive plant and are one that needs more attention then other's ! reminds me of my ex girlfriend !!, maybe ill call it Charlotte lol anyway thanks for taking the time to reply.
Arran