In my airline it is possible to report around 4-6pm for a two sector/four hour flying/7 hour duty day (or for a one sector five hour flying day) and then be told to hang around for a few hours because you are now going on a 14-16 hour Ultra Long haul sector (and then be away for home for 5 -7 days)
This happens regularly - it has been going on for some time and all the authorities know about it (MORs etc etc).
I don't know about anybody else but if I think I am working from 4-6pm to midnight I get up normally. When you then report to be told you are going to fly all night and half the next day (as well as be away from home for several days - unplanned) I find it stretches my physical endurance.
I don't want to say anymore I might get sacked or demoted with the others.