About Lesson
It is my belief that you can easily install formations if you know how to teach them correctly. Make sure your system can move players around with simple tags or key words. How many formations you have is up to you, but as a play caller, it is best to be able to get into as many formations as you may want to and then trim back.
You need to go through the process of thinking through all the formations that you may want to use.
A few words of caution – make sure you can run most of your offense in any formation you pick. It is easy to stop an offense if they only run one or two concepts from a formation.