You should only strike the guitar string with a small amount of the plectrum because using just the tip reduces the surface area that hits the string, which minimizes resistance and friction. This allows the pick to glide smoothly and quickly across the strings, making it easier to play fast and precise notes. Striking with too much of the pick can cause it to catch or drag on the string, slowing down your picking hand and causing tension. Using a smaller part of the pick also improves control and helps maintain consistent speed and accuracy when playing faster passages.