Turbulence is rated into three levels
Slight - continue service with caution
Moderate - service may need to be discontinued or modified
Severe - sit at station or in nearest spare seat
I realise that the company wants to get the most out of there crew but also putting the carts away everytime the seatbelt sign is switched on is also impractical. We are told when we are expecting bumps and we adjust the service accordingly.
The Cabin Supervisor or any member of crew can decide when they have had enough of the bumps and halt the service.
I have not felt the need yet to do this yet. Which could be down to luck or the sheer fact that our service doesnt start till the bumps stop or that the service is over well before the bumps begin.
I generally find that most of the turbulence is closer to the ground. During cruise on most occassions the flying is smooth.