hi i started doing uworld system wise i{ time mode, unused} and iam getting 72 to 76% avg .which way is best random or system wise.could any one please advice.iam planning to write test in 2 months

hi,
i think if you have already gone over the material once then it would be best to go through Random mode and practice in Timed Mode as well so you have trained yourself.
I'm working on System only right now for the subjects i'm scoring poorly in. Otherwise you should do the All Subjects Timed mode.
Good luck!