Part of the significance of these primary landscape components is understanding how water moves in relationship to land shape [topography]. Water is the basis of all life on earth, and the limiting factor in most agricultural production. Managing water effectively is crucial for future-proof resilient food systems.
What you notice if you get a map out is that the valleys are a small percentage of any landscape, while ridges make up the majority of the landscape. In Yeoman’s work, He observed how valleys tend to have adequate water and that ridges tend to dry out, rendering them unproductive.
That was in a Mediterranean climate. Following this patterning is still very useful in any scenario as it can help alleviate wet spots, hold water on the ridges and in the ground itself when it is lacking, accelerate soil building, aid tree [canopy] planting and allow better infiltration of seasonal rains amongst other benefits.
The break-up of hard pan areas is also vital to re-condition the terrain. A 'new-take' on the humble plough can be used to regenerate the water table and mitigate against flash flooding during heavy rains.