Judging based on how much time someone spend on their workout is a very inaccurate to gauge how well their exercise is. There's just too many factors like how pack the place is, so the wait time to jump on the equipment will vary. Also, the recuperation rate for each person's body between sets is very different that would skew the total time as well.

A better way would be to list down the exercises you do, i.e. number of sets, reps, cardio type and duration, etc. Even then you'd probably have to factor in the skill level of the person, i.e. an beginner will naturally take a different amount of time to hit the cardio rate of an intermediate.