Interesting.
In high school my kid was projected to be the 8th or 9th man on his team as a Junior, playing for a coach who only played 6 or 7 players (on purpose). But he had great court vision, though he had never worked on his "skills." (partly because he devoted his time to each sport he played only in its season - soccer in the Fall, basketball in the Winter and baseball in the Spring. He was also just 5'11" but had the skills of s defensive forward - and the 2 best players on the team were the 2G and a forward. We persuaded him if he wanted to get in the rotation, he needed private coaching to improve his GUARD skills (ball handling and more consistent outside shooting - his defense was already amongst the best on the team) ... he had to be able to play PG if he wanted to play. This video reminded me of how my son's private individual coach kept working, working, working him on several very specific drills to develop the muscle memory of the skills. FYI - he had a set back his Junior year when he broke his wrist playing soccer (still could play soccer, but ended his hoops drills), but by the time he was a Senior, working with the coach, he became the 6th man, playing back-up at both PG and point forward.
Point is: Working individually on skills WORKS, or all levels of players, and is a huge factor in development.
Sorry ... to THIS video: Loved watching players work very specific skills, with one of the best in the NBA - and seeing one aspect that NBA player worked at, repetitively.
I noticed several things, having watched many private drill sessions:
1) Man, Harper is SO fundamentally sound, and picks up the drills LIGHTENING fast.
2) Bailey is so athletically skilled - but definitely needs more fundamentals work. Notice how several times Gianni corrected Bailey on his shot "take-off" on the step back or fadeaway. The focus was trying to get Bailey to lift up off BOTH feet - that you could still get terrific step back or fadeaway with planting 2 feet ... and that Bailey still has a tendency to lift up off just his back foot (his left foot). Gianni explained several times how using 2 feet provides much better shooting balance. When Bailey pounds that into himself, and gets that 2-feet take-off second nature, he will REALLY be tough to stop. Using the left foot, 1-foot launch may work against players with much lesser athletic ability and/or smaller defenders, but it also increases the difficulty of a shot that could be much easier.
3) Bailey is NOT 6'10", no matter how much Pikiell or sportswriters say he is. He is 6'9" at best in this video (not sure when this was taken) - definitely at least 2" shorter, maybe a fraction more, than Gianni (who is 6'11").
4) Both Harper and Bailey showed, albeit briefly, pretty good on ball handling drills.