Actually the whole process is vulnerable to error from a rigorous quality assurance standpoint. From proper ID of the horse, intended distance of the work, to the precision of hand timing by the clockers and accurate recording of the data. After you get all this resolved and get accurate figures recorded, then as a handicapper you have to be concerned with the intent of the trainer/exercise rider. Was the horse being pushed 93% or 82% etc.
. Personally I try to understand the spacing (in days) and distance pattern employed by the trainer and mostly ignore the times.