There are a lot of double team strategies out there you can consider. When I'm playing man defense, I usually like to use double teams if I see the other team has 1-3 players who score more than the rest of the team. Which players I double and how I do that can vary. Using your example above, I might double the sharpshooter and go negative on my defensive positioning (to help with the defense against the post guy). Or maybe I do the opposite and double the post guy and go positive on my defensive positioning. Or if those are the only two legit scorers, maybe I just double both of them.
Sometimes I'll double team a player because I think my weak defender at that position will be targeted. Sometimes I'll switch my best defender to their best offensive player and apply a double team (if I have an elite defender, this has worked really well for me--especially in causing turnovers).
I also recently heard someone say in Discord that if they have a fast, athletic team, they will put "Double Team if leading Scorer" on every player. I've never tried this, but it sounds interesting. I also can't speak to zone double teams and what expected results are--I'm just now trying out some zone teams.
But for man defense, double teams work great, they should be used often, and they work best if you have a solid defensive team.