That part about being able to flip through pages and find what you need from memory really hits. Grease smudges on a certain page, a corner folded down where the torque specs are, that stuff builds up over years and it works like a map in your head. A screen doesn't give you that, you can't feel where you are in a phone the same way. The old guy probably knew exactly which page had the wiring diagram he needed without even looking it up.