When you’re sailing in a lot of breeze, your boat is usually overpowered. Because of this, finding more wind velocity probably won’t help you go much faster or point higher. In fact, in some cases a strong puff might even slow you down.
A good wind shift, on the other hand, can be much more valuable. It will instantly move you to a higher ladder rung and allow you to aim closer to the windward mark. That’s why, in windy conditions, it’s better to sail for shifts instead of puffs.