This pull-apart variation is great if you struggle with activation. You may be lacking the ability to externally rotate to create maximal tension through the muscles and position at the shoulder joint. So how do you fix this? By simplifying the dynamic component of the movement.
After the initial pull-apart driving the hands away from each other and flexing the back hard, one hand is going to rotate up into the overhead position while the opposite side will come down to the side.
The top hand will move into the overhead position, maintaining the tension in the band and externally rotating to pack the shoulders and keep in a centrated position. The bottom hand will reciprocate this movement, bringing the arm down to around 45 degrees and moving into internal rotation.
People rarely need more shoulder mobility. If you struggle with keeping your shoulders healthy, you need better stability and control through the range of motion you have.
Mobility isn't a cure-all. If you want healthy shoulders you can't depend on doing the same old stuff that's never worked in the past. This is why I love dynamic stability drills like this one. You can do it before ANY upper body lifts.
What makes this drill so powerful is the dynamic stabilization of the shoulders moving into elevation, depression, internal rotation and external rotation, all while coordinating the movement with the entire upper body and spine.
Move slowly and keep maximal tension through the band at all times. After a peak hold at the top, you'll alternate and bring the opposite side up. The movement pattern itself is similar to the star pattern pull-apart, but you're focusing on dynamic stabilization instead of training active ranges of motion in the overhead and shoulder to the side positions.
"Feel" your way to perfect execution. Move slowly through 2-3 rounds of 5 reps on each side to prep the shoulder before your next pull-emphasized training day which involves things like pull-ups. Maintain glute, core, and shoulder tension while actively contracting throughout. The more focus you put into this, the more you'll get out of it.