Preheating your pan before adding fat can reduce real cook time because the food starts cooking on a ready surface instead of waiting for the pan to heat up. When oil goes into a cold pan, food often steams, sticks, or releases moisture before browning begins. A hot pan helps oil spread quickly, improves searing, and gives vegetables, chicken, mushrooms, potatoes, and fried rice better texture. The exact time saved depends on the pan and recipe, but the habit is simple: heat the pan first, add fat, then cook.