I think the concept of having to play players out of position to train them is completely unrealistic and a poor game design choice
i think it's an acceptable trade-off, but not for fundamental skills like the two defenses for our poor SF
Again, you don't have to play SFs out of position unless you want to. Both ID and OD have training regimes that include the SF position.
i admit i deliberately ignore 3-roles and team training regimes, because i'd like to train my players and actually see them pop