This research examined the focused design, elastic design, energy decoupling, and torque roll axis (TRA) decoupling methods for mount optimization design. Requiring some assumptions, these methods are invalid for some load conditions and constraints. The linearity assumption is advantageous and simplifies both design and optimization analysis, facilitating engineering applications. However, the linearity is rarely seen in real-world applications, and there is no practical method to directly measure the reaction forces in the three locally orthogonal directions, preventing validation of existing methods by experimental results. For nonlinear system identification, there are additional challenges such as unobservable internal variables and the uncertainty of measured data. In addition, nonlinear system optimization analysis is hampered by the challenge of analysis of more than two co-dimensional bifurcations as well as the locally multiple minimal values’ problem in high-dimensional space. Therefore, we must confine our analysis to the linear problem. Per the prevailing decoupling concept, the response decoupling (RD) method in time domain shock response analysis is discussed in regard to its application in shock response analysis. The proposed method is particularly applicable to transient load cases (e.g., vehicles traversing bumpy roads or torque impulses due to shifting). Design optimization and comparative analysis are implemented to further verify the proposed concept, and the feasibility of the proposed method is validated by statics and shock response calculation results. The numerical example compared four design methods, and the results showed that the new design can achieve lower vibration levels and reaction forces in multiple directions. Finally, the suggestion for further research is briefly mentioned.