What types of changes are easiest to learn and often result in rapid improvement in performance?

Pre-swing adjustments are often considered the easiest changes to learn and can lead to quick improvements in performance because they address the player's setup and stance before the actual execution of the swing. These adjustments are typically simpler for players to understand and implement because they involve fundamental aspects of their posture, grip, alignment, and positioning relative to the ball.

Since these components are established before the player initiates the swing, they can significantly influence the entire swing's effectiveness and mechanics. Making a successful pre-swing adjustment can lead to immediate positive changes in the outcome of the shot, allowing players to adapt more quickly and see results in their performance.

In contrast, in-swing adjustments require real-time modification during the execution of the swing, which can be complex and challenging for players to manage. Follow-through corrections and post-swing alterations often involve more nuanced changes and a deeper understanding of the swing mechanics, which would typically take longer for players to fully integrate and feel comfortable with. Therefore, while all types of adjustments can contribute to improvement in a player's game, pre-swing adjustments tend to produce the most immediate and noticeable results.