@DoubleD
Being a good leader is 100% tailoring the right message to each underling.
Your trainer told you what works for him most of the time, which is a valid point, but applying his approach to everyone will definitely lose you top talent that has an ego problem or worse, someone who would be great if given freedom, vague guidelines and a clear goal.
On the other hand, it might not be worth the extra effort of tailored approach if you don't have any stake on the business/project. Trade-offs...