I've never understood why it is that you're supposed to line
horizontally, which has always struck me as a damned awkward thing to
do. Provided you make sure the seams of the lining and top layer
don't coincide - which is easy enough to do - why can't you line
vertically (I always have done so myself).

David

interesting point David, I don't really know why, but I know that it is done
and i have done it myself and it wasn't as hard as first thought. i assume
that the cross laying is done for a little extra strength and insurance
against possible cracks reappearing, though i am not sure how effective it
really is as the paper doesn't really have a directional grain structure.
perhaps it's because it's easier to hide the underlying seam by laying
across rather than with, because gravity and natural shrinking of the paper
along it's length stretches the top layer out and the capillary action is
less likely to pull it in to the underlying seam.
perhaps it's both of the above ;-)