Here's my take on Season 3:
1,2 – You know what happens when you assume…; It's okay to give your friends credit instead of doing a hard job on your own.
3 – It would be great to be everywhere at once, but better planning is the superior option.
4 – Bullying is a real issue with troubling consequences. Those who bully often have insecurities which cannot be taken at face value. The important thing is that an adult should be consulted if this arises.
5 – Sun Tzu: “The supreme art of war is to subdue the enemy without fighting.”
6 – Anxiety is real; even those we admire experience it. Take solace that it can be overcome.
7 – Above all else, be loyal to your principles.
8 – It's better to spend time with your family than plan exorbitant activities.
9 – Gratitude is great, but that's what friends do; don't lie to your friends.
10 – Discord: "I liked it better my way but … when you're friends you can't always have things exactly your way all the time."
11, 12 – Remain calm in spite of whatever might happen, and own your mistakes if you make them; You know what happens when you assume…
13 – Be true to yourself. Musicals are awesome. Everything is going to be ok.

This should be taught in school as an example of confirmation bias and selective acceptance. And this is coming from someone who hated the finale WHY CAN'T ANYONE BE INTELLECTUALLY HONEST.