> I throw all my notes out as soon as I finish writing them.

I do the exact same thing, and haven't met anyone else that did it. I thought I was a weirdo all this time! My learning process is (as theorized by me):

1. Hear/see instructor say something

2. Mentally digest and understand it

3. Write down the product of understanding it

I think #2 is the most important step, and the big purpose of step #3 is validating that I actually performed step #2.