It's in innate part of the player and by far the most challenging thing to change. Sox have been working with Robert for 5 years on this, and his solution appears to be just taking more pitchers by default, for example:
Robert is actually swinging at fewer pitches in the zone vs his career. Is he swinging at fewer out of the zone too? Yup, so he's just squating on more pitches. Which I'd argue is bad because he's also making contact on fewer pitches in the zone which is more important than making contact with a few more pitches out of the zone where the contact is weaker. This overall approach, so far, has hurt Robert significantly. He's getting killed by the fastball up and in because he's late because he's worried about being patient. Robert changing his pitch selection has effectively slowed his reaction time imo.