I managed to get away again on Wednesday evening.
There was some extra preparatory work required first (such as removing brackets for the central tractor of the roller door) so I did not get to install the sheet until quite late.
Unfortunately, once you start installing a sheet you can't just walk away and leave it - the gyprock adhesive will go off leaving hard lumps under the purlins.
I didn't get to leave until 10:30 pm so had quite a late night to bed.
I'm making slow but steady progress.