If you haven't done a loadsheet in the last 15 years because you allways get provided one by cetral loadcontrol or something like it the re-learning on the spot can be quite unpleasant.
In theory every pilot should be able to paint one up in a couple minutes, however that is theory and remembering what you learned in basic training 15 years ago ain't easy.
I flew once in an operation like that, however we then started to do the occasional charter flight where we had to do our own loadsheets. It sometimes took over an hour during cruise to prepare one for those who had been longer out of touch with paperwork like that. In my current outfit it is not a problem, we do a loadsheet every turnaround, however it is done on the EFB and then just printed from ACARS.