I believe the assumption that cruisers simply 'just raise' a (dacron) sail and hardly ever 'shape' a sail is a fallacy.

Granted, most cruisers haven't done much studying on the dynamics of sail shape but they have a lot of time on their hands. When you're going 3 days, you're reading the weather, looking at instruments, monitoring the sea state, making calculations and more. Another part of it for a cruiser is that you know your boat. What works on another might not work on yours. 'Heaving Too' being one example.

Every cruiser I know that does it seriously works his sails. Not racing mode but always looking for another 2 tenths of a knot.

And the second half. At least as important as speed is making the boat comfortable under way. Adjusting the sails, speed and direction for comfort. An adjustment on a main that's perhaps not perfectly efficient might make life on board a lot easier.

Any cruiser that's a cruiser shapes his sails.