Here is my opinion...
We have great analysis tools today to calculate all sorts of loads and ressponse. From your transient hydraulic analyis you can generate time histories to represent the hammer load for every leg in your system. And you can push that data through CAESAR II and wade through the results to evaluate your design. Pure number crunching.
But engineering is the practical application of the science using experience. Many hammer issues are addressed, not with analysis, but with construction and operation guidelines. If analysis is required, a more general, wide-ranging approach would be appropriate when specific time history data varies. So a static equivalent load applied to the longer runs might do a better job in bracketing all the possibilities and confirm a more reliable design.