I always slept more soundly when I was getting a "shake" versus relying on my alarm clock. It's very comforting to know that you're absolutely going to be woken up when you asked to be and not have to worry about your phone being on charge or accidentally sleeping through an alarm. It also meant you didn't have to do time zone maths when you went to bed and that your alarm wouldn't wake your cabin mates.
All this to say - yes. Fantastic fucking sleep. The cranked AC in the summer the open windows even in the depths of winter helped too. Deepest sleep I've ever gotten.
The meaning was that if you didn't get out of your hammock it would be cut down with you in it. An abrupt and rude awakening and potentially leaving you with a chore to fix your hammock before you could sleep again.