I think it depends at our HS. I don’t buy that if you let one do it, you have to let everyone do it. Players have to earn certain privileges and I feel like calling your own pitches is something that you can earn.
A coach might let a senior, three-hole hitter with three years of varsity experience swing 3-0 but surely, he would not give a first year varsity sophomore, seven-hole hitter the same privilege.
Well, the same can be said for some senior pitchers versus other pitchers.