IDK supposedly executives are paid to be on top of things, be responsible if they go south (but boards and golden parachutes protect them), and work however many hours it takes to make the important decisions.
So if their time is divided then my guess is they won't be doing it very well. If they are all face and PR then perhaps AI will replace them.
IMHO, this is the difference between the Berkshire Hathaway model and the Apple model.
Good leaders should probably invest a lot of time in developing a deep and talented pipeline of other good leaders, so that the current leader can be replaced.
Bad (but still effective) leaders leave the company flying off the edge of a cliff without a successor when they exit. Usually because they played politics and blocked anyone's rise who could challenge them. (See: PLO)
So if their time is divided then my guess is they won't be doing it very well. If they are all face and PR then perhaps AI will replace them.