Mixing Batter Too Much
During cooking, breads and croissants expand and become puffy thanks to the gluten network that was created when you mixed flour with liquid.
That same gluten network will make your dough tough and unpleasant if you work on it too much, especially if you’re planning on making a pie or cookies. The less you work, the better. As long as everything is well incorporated, you’re good to go. Just don’t forget to also chill your dough, too!