Just pointing out that 5mm = 0.196 inch. I mean look at that on a ruler. It isn’t much. That’s less than ¼ of an inch, about 3/16 of an inch. Unless you’re a weight junkie…the only strong argument I’ve ever heard for shortening up crank length (when the length you’re using is appropriate) was from a guy who frequently raced criteriums. Pedaling through the turns…with the shorter cranks…allowed him to lean into the turn more (while still pedaling), and thereby faster through the turn. — Dan