I can not understand why Web Mercator projection is strictly square.
In my mention:
We have a planet as a sphere. We have 360 degrees of longitude and only 180 degrees of latitude. That means if we measure equator it gives us 360n, and if we measure meridian from pole to pole, it gives us 180n.
Additionally WM projection does not project 80-90 latitude. This means we have linear size about 360n x 160n.
The planet as an ellipsoid is nearly spherical. The diameter in equator section is not 2 times larger than diameter between poles, the ratio De/Dp is about 1.1, not 2x...
This means if we project 360nx160n to a square, the scale of one side will be >2 times bigger.
But WM is equiangular (conformal) projection, this means that scales should be equal, or nearly equal due to some features of projection, but not 2x times.