"Sharing knowledge in the business world, never. That's a great way to lose a job."
I think that depends on the role and the organization.
Generally organizations do not like to loose valued individual contributors unless the organization is somehow pathological (I know those exists).
A programmer that delivers value is always worth more than his or her paycheck. If you can dump his load to a more junior dev then that's great, there are other, more important things always that need doing. That is, if the business is growing.
The delta comes from my incredible work experiences / organization management in the Marines and then working for selfish and incompetent bosses in the civilian side. (I have had bad luck on the civilian side in the past.)
I agree if an employee needs to fight for leverage over their manager then hiding your notes is as good way to do that as any. But if you need to use this tactic it's a clear sign the workplace is not healthy.
So, instead of as general advice "never show your notes" - I would rise to a level above - first in good faith, but in a defensive posture observe if your employer rewards co-operation or selfishness - and then choose your tactic accordingly.
Falling under incompetent management is a double injury - the incompetence is both professionally reprehensive and being managed incompetently just hurts.
I'm sorry you've had this experience on the corporate side.
I see in one of your other comments that you work for yourself now, so this unsolicited advice probably doesn't apply to you. But I'll leave it here anyway.
I've had plenty of candidates ask me how I or the company help employees grow, and what it takes to advance.
I typically see this as a good sign and I explain the career ladder, explain how promotions work. Explain how I would help in their growth.
If they don't have good answers for this, it's quite a red flag.
You can also ask about collaboration and what kind of work is rewarded.
I think that depends on the role and the organization.
Generally organizations do not like to loose valued individual contributors unless the organization is somehow pathological (I know those exists).
A programmer that delivers value is always worth more than his or her paycheck. If you can dump his load to a more junior dev then that's great, there are other, more important things always that need doing. That is, if the business is growing.