Articles on bee navigation and the language of the bees often note that bees seem to have the ability to extrapolate floral targets. That is, if they are told to go to one location one day, then another location the next day, they will know to head a bit farther along the line connecting the two locations the third day. Most of the articles note that there is no known reason for this ability.
Obviously, these articles were written by experts on bees, not experts on flowers. Flowers on hillsides often follow regular, linear patterns of blooming, often starting low on the hillside and blooming their way uphill. Bees, being experts on flowers, know this and use their knowledge to save time in hunting for prime nectar.