Walking in France in the summer is an exercise in early rising, as the heat soon makes arduous what would otherwise be a pleasant stroll. This being the case, it is better to have the low sun of morning on your back and not in your eyes. It is surprisingly annoying having to squint into the sun while walking.
Because of daylight saving, the sun is not at its zenith until about 2pm, by which time any sensible walker has finished for the day and is stretched out asleep under a tree, so there is no problem with getting sun in your eyes later in the day.
The geography of France lends itself to this pattern of walking, in that everything west of the Massif Central descends gradually towards the Atlantic, allowing the walker the double advantage of a generally downhill progression and a shady face.
The pilgrimage from le Puy is an example of a well-oriented track, going in a south westerly direction all the way to Saint-Jean-Pied-de-Port.