It drives me crazy, especially when I play large households. I now use the autonomy tuner in MCCC to stop it. They aren't allowed to cook autonomously anymore. When the leftovers are gone, I'll pick one to cook a party meal. If one of them gets hungry and I click to autosolve, I can tell when they were planning on cooking a fresh meal despite there being leftovers in the fridge. They'll just stand there and wave their hands. It's a bit of extra work to click on "grab leftovers" when this happens if they don't grab the leftovers autonomously (sometimes they do, sometimes they don't), but it's far less annoying than them all raiding the kitchen attempting to cook single plate meals while one sim is trying to make a family or a party size meal.
