To finish the service as quickly as possible and get most time in the bunks - happens far too often.
It happened when I travelled to SFO as a pax not too long ago - flight time around 11 hours - crew were out of their seats less than 2 minutes after take off - and got over 3 hours in the bunks - on a trip as SFO you should have 2 hours and 15 minutes in the bunks.
6 of 11 hours in the bunks - that's 55%!