In Puzzle 3, you would like to balance rack while minimizing options for your opponent. While ENVOY scores the most points and keeps the best leave, it also leaves the O next to the bonus square, letting your opponent score well with a potential clunky rack. ENVY scores one less point and keeps a slightly worse leave, but is still a better play. However, NAVY is a better play since it keeps a slightly better leave (A and O are antisynergic) and blocking a decent scoring spot using column m.