skol,
The seat belt sign is switched on in cruise for no other purpose than the expectation of, or the actual occurance of turbulence.
An SOP which requires customers to strap in yet allows the cabin crew to just keep wandering around with 200kg carts is insane.
I know of 2 US airlines that used to have a policy similar to what you describe but both of them changed about 5 years ago.
It would seem that it is time for you tell us all which airline you work for?