I cannot confirm that. One centrally high-mounted wall access point per floor covers the entire large solid building including the garden
That may work for you, but in general, the design is like this. For example, I have a wall access point with the following radiation pattern:

and a ceiling access point from the same series:

As you can see, the coverage with the ceiling access point is more even in all directions. This applies especially to 5 GHz. Of course, this does not mean that wall APs are bad or that you can never cover a house with them. It’s just that they are usually not ideally designed for that.