> If the junior does not come to me with a question, he might spend 20x actually needed time on the problem.

*2000x. Very true.

> Different people need a different approach. It is quite likely that I am doing something wrong in how I provide help.

A thousand times this. If you think they couldn't possibly misunderstand you, think again. Then again. Every time.

> Some people are just stupid.. "Against stupidity the gods themselves contend in vain".

Sure, but check with someone else--someone outside of your comfort zone--before confirming that.