Some people, including myself believe that the game engine only generates blocks on shots that are going to score. This means that shot blocking does not have an effect on shots that are already going to miss.
I think shot-blocking is useful, but not necessary if potential limits it or you want to train other things. I think with an all-star potential player, 6-7 SB would be plenty and it would be more beneficial to focus the cap space in more ID or secondaries.
Murray/Harris/MPJ/Grant/Jokic - 2020 NBA Champs