different fields have different conventions regarding what a given authorship position implies in terms of work contributed to the paper. Some place very high weight on the last named author, others on first named, among many other permutations and subtleties. There's no single rubric for deriving relative effort from author name position.

part of this is contingent upon citation formats used in different kinds of publications (and thus different fields) where long lists of authors are condensed to one two or three at most.

this is not even getting into more locally scoped, second order inputs such as any given department's traditional handling of advisor vs. grad student power dynamics.