SRENNAPS (and others)
The sort of shift work being talked about is:
RS15 on SAR
Manning Air Traffic
Maintaining the radar watch on UK Airspace
and so on.
All such shifts are manned on a digital basis - there is nobody spare to cover. You usually can't leave the building. In some jobs you cannot leave your post at all without a formal relief.
Please realise some of us just can't down tools and go do triv elsewhere.