A lot of it is trial and error and is going to depend on point of sail, wind
conditions, etc. Generally you get the right lead angle when your leeward
jib telltales all lift at the same time. That tends to maximize upwind drive
and make the largest 'sweet spot' of jib angle. I removed the blocks
altogether from the deck at the side of the cabin and use my genoa blocks on
the outside of my toerail exclusively now, at various positions.