Saves time, yes, but crucially, it can be added at varying percentages as a single concentrate to give a different effect than it would in its original 9.5% form.
Many thanks to @cindy99 and @BlueNoze, that's brilliant! My very favourite solution, though, is that @OccultScientist incorporate it into the juice calculator so that I don't even have to think at all.
Makes sense, you are creating your own flavour blend - carefully check anything anyone comes up with in a calculator to make sure there are no rounding errors.
Risk is of course forgetting that you already have a certain flavour in your blend and then add that flavour again?