Post Session Reflection

My mate spends 10 minutes after every session reflecting on how the game went and what he can do better next time round. He makes notes and makes sure to incorporate the ideas next time.

I love his approach to becoming a better DM and believe it can work as a player too. AS such I have started doing some reflection myself.

My question is, do any of you do anything similar, and if so how do you structure this reflection?