When feed plan is approved, farm managers will plan operations around expected delivery dates. There may be logistical and planning reasons which require the feed mill to commit to the agreed upon dates, one such an example provided is when it snows, and farmers have to plan for plowing services to clear the road for scheduled deliveries. Once something like this has to be coordinated, deliveries optimized by flock performance take a lower priority to showing up at a certain times and dates.
The feed plan fixed date feature will force the regeneration process to lock down specific delivery dates and prioritize creating records with those dates.