Final answer:
Leaving batter to stand too long after pouring can lead to overdevelopment of gluten and escape of leavening gases, resulting in a denser and less airy baked good.
Step-by-step explanation:
When baking, it is generally advised not to let batter stand too long after pouring because this can affect the final texture and rise of your baked goods. Most batters contain leavening agents like baking powder or baking soda, which start reacting as soon as they get wet. If the batter sits for too long, the initial bubbles that give the baked good its rise will escape, leading to a denser product.
Furthermore, gluten development is also a concern. The longer the batter stands, the more the gluten has time to develop, which might be undesirable in items where a tender crumb is preferred. It's crucial to follow recipe instructions carefully to ensure the desired outcome in your baking.