I've always felt this way ever since 2007..
I had a fantastic teacher in my foundation classes that taught us drawing and all the details and technicalities that will improve one's drawing.
It was probably our second class in our second semester, when he came in and announced that we were going to be drawing our own portraits.
He then taught us the symmetry of a person's face/body.
How your foot is always the same length as your forearm (elbow to wrist) and all of that.
The corners of lips are usually right below the middle of each eye.
The space between both eyes is an eye.
Your ears starts on the same line as your eyes.
The nose fits right between the eyes.
Until today, every time I doodle for fun, I always end up thinking about everything that was taught and I will always inadvertently try to stick to it.
Perhaps it isn't such a good thing that I allow such 'rules' to dictate my drawing but I find that it works for me...
And I suppose that will be the ONE class that I will always thank the powers that Be for.