During taxi to take off and on final approach after the cabin is secure, the most senior crew member comes on the PA to say 'cabin crew, please take your seats for take off [landing]'.

I have been observing what happens next in the past 20-odd flights this year and can non-scientifically report that in 75% of instances, crew members were still milling around after the announcement - closing cupboards, having a drink, a chat, changing their shoes etc - sometimes for 30 seconds, sometimes for a few minutes.

The other day the announcement was made about a minute after we had left the gate at T5 yet it took another 10 mins just to cross the airfield, without any delays, so the crew was still up for a good 5 minutes.

Why is this announcement not strictly respected by the crew?