Personally, I think it has something to do with the factors you consider when designing an independent foundation. If the axial force, bending moment and shear force at the bottom of the column are calculated in the calculation of independent foundation, the ground beam can be set under the wall of only one floor. If the bending moment and shear force at the bottom of the column are not considered in the calculation, only the axial force and the equilibrium bending moment of the foundation beam are considered. At this time, the position of the foundation beam also needs to be seriously considered. In the second case, the single basis calculation is simple. The first method is complicated in calculation and drawing.