Some providers do calculate reasonable fuel between DEST and ALTN, however - for whatever reason - the printed routing on the paper is greatly simplified. Only way to find out is to analyse an in-service event.
It might not be too bad after all. Most of the providers allow for different customer configurations, it is hard to compare.
My biggest scare is a lenghty GA track you cannot get away from, with speed restrictions preventing you to go clean. THAT is never accounted for and the difference is MASSIVE.
FD.