Awful route for this sort of behaviour is LHR/LCY-FRA. Full of business people on both sides of the curtain who switch their phones on the second the plane touches down.

Then again BA seems to be a lot stricter about rules than Lufthansa. The split second between engines shuting down and seat belt sign going off is a fascinating moment: LH pax get up, BA pax remain seated. The occassional BA pax to get up is quickly reminded that the seat belt sign is still on.