Break Time In Nursing

there is a ward with four cubicles and each cubicles need one registered nurse and enrolled nurses and our break time is from nine clock to one clock afternoon. each of us have one hour break time. we are told that two out of four staffs can go for break at one time. but now our nurse manager said only one staff can go for break at one time but nurse manager never assign who go which break. fall risks decreased but staff complains of tired due to very late to