It helps you learn the grip. Use it until you don't need it any more. I use it with every student.
Casey learned the grip with the old turbo slot gloves, before the bat jack.
I have 2 hanging on the wall above the yellow and pink balls.
The older ones had a thicker pad (dark gray) and did not roll over to Velcro.
You can use the bat jack with turbo slots and it will help reinforce the grip and make you use the turbo slot gloves the way they were designed.