Why are natural zones on the continents not everywhere consistently replaced from north to south?

The formation of natural zones depends, in addition to the climatic zone, also on the relief, distance from the sea, etc. On those continents where there are high mountains, natural zones change with height. Also, the mountains block the path of precipitation from the sea side, and on the other side it becomes arid, which also affects nature. If the continent is as large as Asia and North America, then, because of their length from east to west, precipitation does not always reach the center, and another natural zone is formed there, and another in the coastal part.