This Book of the Law shall not depart from your mouth, but you shall meditate on it day and night, so that you may be careful to do according to all that is written in it. For then you will make your way prosperous, and then you will have good success.
Joshua 1:8 ESV

Every good leader should study Torah (God's Law). Success takes many forms, but it can never be "good" unless it conforms to God's instructions.