Years ago I spent the summers working on an arable farm. The main crops were spring onions, cabbage, and runner beans. These would be picked from the field, given a quick wash and thrown in the cold store. Leter in the year cabbage would also be dunked into preservative before going into the store as they were coming off the field much faster than they were ordered and could be in store for months. The packing shed would take produce out of the cold store in rotation and pack for the supermarkets, including sealing into bags or film and applying the best before labels.
Depending upon the order levels and time of year, stuff could be going out labelled with widely differing best before* dates (days or even weeks difference in the case of cabbage) even though it came off the fields at roughly the same time. In the height of summer, spring onions would be packed during the day, with the actual order only coming in mid-afternoon. It simply wasn't possible to fulfill the order after it had arrived, so the supervisor would work to an estimate. Any that were packed but not sent out that day would be sent out the next (or a couple of days later if it spanned a weekend) - with an extra day or two on the best before label. Sometimes stuff would have a label removed if too many had been labelled up and subsequently go out with a later date on it.
After this I treated all such labels as, at best, advisory.
*using "best before" as a generic term, maybe it was "use by"
