[Richard Farrant]

Tony and Ian,
Another reason for not having many layers of rope on the drum is due to "effort required". Maybe experience told them of the usual length of pull required, the more unused rope on the drum, the more effort required to wind the handle.
Each layer will increase the load on the operator, the only other option is to use some thing like a Trewhella rope grab, to clamp on the rope down its length in order to start on bottom layer.

Of course if shortage of steel wire rope then it could be the real reason.

I spent a good deal of time repair and testing all kinds of winches for the army from hand operated winches, recovery vehicles through to 30 ton winches on Caterpillars. Each layer on the drum on a vehicle winch, reduces its pulling power before the cut out trips in.

regards, Richard