There are cases where the
Rasul (the Messenger) p.b.u.h did not spell out specific criteria for a certain condition/situation.
For example the minimum distance traveled to qualify as a musafir (passenger). In this instant,for example would the criteria to be a traveler depends what the uruf of the society regards the condition of a traveler.
Or would it depends on the individual judgment and situation i.e. if he travels in a comfortable car, the distance to qualify as a musafir would be much further than if he travels by foot.