I agree that overthinking is not the same as being smart.
The brain is a muscle that must be exercised, and overthinking is like doing reps.
Why else read books?
Real intelligence is knowing when to think and when to act.
Actually, that's a sign of a lack of it.
Those who act first had less questions, intelligence stalls.
A clear mind makes better choices than a busy mind. Peace comes from balance, not from endless thoughts.
A mind acting rushed is not clear.