Regarding retail - I'm doing a bakery and originally was using the standard display cases. I had one freezer case (which Sims can buy directly from the case without you having to ring them up.
As my plan was to bake replacement stock, it made more sense to get rid of the standard cases and put all the stock in freezer cases. This means no restocking time spent. Just spending time baking.
But here's the unexpected benefit. About half the time, when a sim buys something from the freezer case, they will then set the item on a counter or even on the floor. You can then immediately grab and drag it back into the freezer case to be sold again!
I have one employee set to cleaning. When nothing needs cleaned, she's chatting to customers working on sales. Now that I don't have to pull her off to restock, her time is better spent. Also, since I restock my own baked goods that sell, my overhead is MUCH lower (and even lower when I can resell the same item!).