My sister (who can whip up a fabulous meal for 12 with an hours notice) says it’s all in the pre-prep.
She’s got ziplock bags of sliced onions, cubed carrots, mushrooms in her freezer- arranged like books on a shelf so you just quickly pull out the one you need. She’s got loaves of home made bread, cookies, pounded chicken breasts. Always a few bags of stew which defrost quickly in a bath of water and then get reheated.
She would rather devote an entire Sunday to making two months worth of meals then stress if she hits traffic on the way home from work. Then when you get home it’s rice into the rice cooker or boiling up the pasta, a quick salad and you’re done.
I wish I were that organized. So sure- if we all had the mushrooms and onions sliced and ready to go into the pot the recipe prep times would be accurate. But if you’re first washing the mud off the mushrooms when you start- I find I’m already behind!