Have worked for a few different outfits,
One used the little red/green flip card on the centre console for cabin secure (senior phoned the flight deck to pass cabin secure)
One used chimes AND PA (again, senior phone the flight deck)
The others all used the cabin secure button/ring, and flight deck made a PA.
However I noticed in 99% of cases where they used the PA, it was done while still on the taxiway waiting for the final turn onto the rwy so they couldn't possibly have thought they could also take off
Framer, have you never flown in Asia/Africa/Middle East? Most of the pax could not give a crap if you are about to take off, if they want to get up as the plane is going down the runway, they'll get up....
nothing to do with whether the FAs are 'watching' or not....
If the flight crew didn't get cabin ready by the last stages of taxi, they would call us, no assuming its ready. (I guess this depends on where it the checklist it is, but whenever they called me, it was well before we were next in line for t/o)