Food releases moisture as it’s cooked, so leave room for the steam to escape. It’s easy to overcrowd a pan when you’re in a hurry, particularly if you have to brown a large amount of meat for a beef stew. But the brown, crusty bits are critical for flavor, particularly with lower-fat cooking.
A soggy batch of beef going into a Dutch oven will not be a beautiful, rich, deeply flavored stew when it comes out, even if it does get properly tender. This browning principle applies equally to quick-cook foods like crab cakes and chicken breasts. Leave breathing room in the pan, and you’ll get much better results. If you need to speed things up, use two pans at once.