There are two ways to achieve success: hire the best people for the maximal responsibilities, or hire with just enough skills and supervise them at depth. You would think most executives will go for the first and you will be wrong.
Some of the staff maybe plotting for a mutiny, or less deviously, wouldn’t mind the executive to fail. There are capable and ambitious ones who have been waiting for the opportunities. They create troubles: bickering, distractions, or even sabotage. A savvy executive is better off ridding them.
Many executives, in their hearts, like to be indispensable. Few of them have any real career opportunities after having risen to the top echelon. Sitting on the laurels is nice and comfortable; a good “succession plan” seems like unnecessary works.
The common strategy is to hire “just enough skills” to do the job and create an organization which internal dependencies and the executive to be the hub for all decisions. This way, no one can replace the one on top. And no one is strong enough for mutiny. The euphemism is “checked and balanced.”
This works, at the price of execution velocity. This is OK if he/she does not have counter-parts or competition. The alternative strategy, is “trust until it hurts, else fire them.”
Give your staff more responsibilities. Stretch them. Demand them to make decisions on their own. Trust them to do good jobs. Monitor for early signs of failure. If you cannot trust them to rise up to this, they should not be on your staff.
This better strategy works really well and is also less stressful for the big boss. It works against the instinct of self-preservation and egotism. Therefore only the best do this.