Using the American example for your future actions not the best idea, their policies more often than not dictated by the litigation culture. Seat-belt signs ON for an entire flight bad airmanship. A good pilot should be able to do his job with confidence.
There will always be pax who NEED the toilet. Old ladies, men with prostate issues, drinkers, kids - plus crew who are required to be up regardless of light turbulence and belt signs. These are the injuries occurring frequently in turb events.
In the airlines I fly with there's always an announcement advising the pax to keep their seatbelts on during the flight even when the 'fasten seatbelt' light is turned off. The majority of the pax don't seem to give a toss about it. Then they complain they've been tossed about.
A decent operation will have this "advice" put as a "requirement" - in theory pax now take responsibility and airline/captain are absolved - to some degree. Untested in court?