The advantage of secondary beam mode input is that the calculation is simple and suitable for manual calculation. The disadvantage is that spatial coordination cannot be considered, and its own stiffness has no effect on the stiffness, period and displacement of the structure. The advantage of main beam mode input is that the spatial coordination effect can be considered, and the calculation results are more realistic in theory. The disadvantage is that the calculation method is slightly complicated and suitable for computer calculation.
The latter accounts faster. But the difference is not big.