Aside from saving time, I think I got into the habit of helping out my sims because of that electronic trash can that pays something like ten simoleons for each household member?
I also like to see my families have their meals together so I usually bring out a dish from the fridge to the table and have one of my sims call everyone else to the meal. That method seems to work much more smoothly than having each sim take a turn at the fridge.