For most shots, 30 seconds is enough time, but I don't want to hit every shot with 3 or 4 seconds remaining. That's just unnecessary stress.
In any given round tho, it's not uncommon to face a tricky downhill pitch, a hard breaking putt, a difficult lie in a strong crosswind, or whatever... that requires a little more thought.
Yeah, I can get the shot off in 30 seconds. I can also play the game with my feet in a bucket of ice and a crown of thorns on my head... but why would I want to?