Someone that follows approach B learns more in a shorter amount of time. Because learning (advancing the frontier of your knowledge) happens when you encounter that limit, recognize it and try to move forward. Rather than dismissing it, which is what A) does.
B) always thinks: what is a better way of doing this? A) never does. Therefore, over time, B) becomes more effective than A).
In mind sports it's the same. You learn more in slow games when you take longer to think your moves. Every pro will recommend you to prefer slow games over fast games.
