Well, it may be recommended, but if the attendants constantly nag you to put them on, then that's the same as required, no?
Only the obnoxiously hard headed folks would argue back and go "since it's a recommendation and not a requirement I will not sit with my seatbelt on, and there's nothing you can do about it."
I’ve never seen anyone be nagged over seat belts mid flight. The messaging from Australian airlines at least is very much that you are free to take your seatbelt off but that it’s suggested to keep it on while seated.
