Why not use the PROVIDE statement for this? It can also handly more than time and date type intervals

One could argue does it make sense to use the parameters if an exception is raised? In the end, the method was not able to fulfill its purpose (you raised an exception). So does it make sense to process the parameters? In my opinion no. I try too to...

I believe its the same behaviour as in this recently posted blog: https://blogs.sap.com/2018/06/21/abap-traps-lifetime-of-functional-operand-values/

This can also be simplified to date_ext = |{ sy-datum DATE = ENVIRONMENT }|. Big advantage with this expression is you dont need an intermediate variable if you want to pass a formatted date into a method!

Actually this result is not suprising. What you are doing is comparing two O(n log n) algorithms against an O(n^2) algorithm.