For the Leigh jig, you can do everything on one side. Last cabinets I
made, I set the left side up for the 8" drawers, and the right side up
for the 4" drawers. Of course, this only really "works" if the
dovetails are symmetrical. If they're not (like, more at the top than
at the bottom, for some reason), then you end up using both sides.
I did 4 big drawers and 2 small ones; 24 total boards. I just cut
them all the same (well, 8 big sides, 8 big ends, 2 small sides, 2
small ends) and put them together later. I wasn't trying to keep
track of which pins went with which tails; the jig makes them all the
same anyway. The drawers came out fine.