I think ball squeezing has a special purpose and is differentiated by that of control and ownership of the man's balls that are implied in other CBT play.
I love to see when a girl literally
"has a man by his balls", and is squeezing them exerting her absolute authority on him. If he is nude, and his naked balls are gripped by her, then her control of him is absolute.
Following is a recent depiction on femaledom.com of this. This photo is fantastic as it reveals facial expressions that match this type of female domination of men. She squeezes his balls extremely hard with his face erupting into sheer agony a debilitating pain, while she laughs and smiles meanfully knowing that her squeezing his balls so puts him in that pain. I really enjoy seeing the girls enjoy these moments so much.