Scalp Exercises and Previous Scar

[Plum]

I am likely going in for a second procedure and was told about scalp exercises. One thing I had not heard before was that depending on how deep the scar runs from the first surgery, these exercises may not be of much benefit. Anyone have any insight about that?

On a related topic, how long should one ideally be doing scalp exercises before surgery? Would a month be sufficient to derive any benefit?