David Allen On "Getting Things Done"

now thats a job, to talk how to do things done.
basically you just talk, talk and talk even more, so that people forget phrase 'just do it' ;)

commitment to what he is saying is a problem

If the brain "isnt for reminding and remembering,"
why do we take tests in school?

He made a broad statement that isn't fully correct. What he should have said is that your brain forgets things quite easily. A system of writing down and organizing your thoughts outside of your mind is much better. The easiest way to accurately remember something is to review it from something, not to recall it from memory. If you asked me to recall from memory all that I learned in physics in high school, I'd barely tell you 5% of what I was taught. If I reviewed my notes though...

Agreed, fully.  However, that certainly does not answer my question.

80% of school is B.S. and is built to build work habbits - not anything relevant

Because once apon a time they thought thats what made somebody smart. Their ability to retain miniscule facts..

Good point, BUT: school is about learning. Remembering and reminding are highly useful, but hardly all there is.

Honestly: why bother your brain and mind with remembering to buy cat food if you could easily outsource it? Better write it down. The only thing you have to remember then is "Look at $note_taking_device" instead of 285 different things you might/could/would/should/ought to do. Makes thing easier AND you can focus on more important things than just remembering.
My $0.02

Because most of what we learn in school is BS, I'm sure you would agree;)

Try the pomodoro technique instead, you won't go mad.