old stuff needs to be pulled to the front, and new stuff needs to be put behind it

As an aside, my “not unethical but does feel a bit like you’re cheating other people” life tip is to rummage around at the back of the shelf/in the bottom crate of a stack of crates for the freshest food. Don’t feel too bad about it especially in a high-turnover shop. They were going to sell the most recent-dated stock anyway, just to somebody who’s not you.