Passing the exams at first attempt is useful because firstly is allows you to move on and secondly, it's cheaper. Needing more than one attempt may also preclude you from "working" for some companies. However, let's be very clear: The content of the exams is little short of diarrhoea. It's applicability to modern aviation is so marginal at to make it worthless. An hour or two on YouTube might be more useful. MEL's, actual met. data (who really cares about the name of the wind - that sort of thing is for a pub quiz) and computerised flight planning have replaced the somewhat optimistic "best guess" approach used in the past. If however, you start working for a company operating in the past (and/or Third World) then your knowledge is still wasted because you'll still be doing it their way.
Exams are just a step in a rather (at the moment) pointless path to getting a license.