My father-in-law is the greatest packer of all time. When my wife went to college, he would pack half of her things in plastic bags to make sure he filled every crevice in the trunk. You see suitcase are inefficient because they aren't flexible enough to fill all available space.
It takes the thought processes of an engineer to pack a dishwasher (new design) until it is full while proposing beforehand the size of the disherwasher needed (design box size and shape). This is done without knowing the number of dishes (detail design) it takes to fill the dishwasher (design space).
Your wife and siblings (fellow designers) will want to pack the dishwasher (design approach) their own way. This must be done without ever looking inside the dishwasher (design not done yet) to see what dirty dishes (detailed component placement requirements) have been placed there. An engineer will pack the dishwasher by using experience and clever placement of the dishes (major components estimates).
When the struggle to fill dishwasher (design to the committed space) properly to get the dishes clean (meeting component requirements such as cooling, wiring, access, testing, etc.) has been completed, one is indeed thankful yet proud of the results. This is why I love proposal through design and production of products.