Maybe they do. But they must do it in secret. We don't see a lot of opposite field hitting drills going on at batting practices. Opposite field hitting should be drilled everyday. That's everyday as in Monday, Tuesday, Wednesday, Thursday Tee work is very good for hitting to all fields.
Soft toss is a good drill.
Hitting in the cage is also very good. But live hitting to the opposite field on a baseball diamond is the best method. It gives the hitter a good perspective of where his ball was hit on the field and it clearly makes evident to him the distance each batted ball travels. We feel this particular drill is a very good opposite field hitting drill. Here's the setup.