Why are the walls erected simultaneously to the same height during the construction of a building?

When erecting walls, you need to take into account the pressure on the foundation, if the walls are erected evenly, then the pressure on the foundation will be even. Under pressure, it can sag and if the load on one side is greater than on the other, the balance will be upset and collapse is possible. And with uniform erection with the help of a level and a body kit, you can control and suppress all errors in the construction site.