I have been told that the first-time pass rate, nationwide, on the initial IRT is around 45%, so certainly no-one can say "most student" overall pass first time. There are many that get a lot better than the average however, and can say so of their own students - inculding two others at EGHH alone apart from PAT (obviously working here I know more about local companies - this is just an example, I am sure there are others elsewhere). This suggests to me that there are also many with lower pass rates, including some very expensive, well-known schools according to people I have met who have attended those schools (that is hearsay so I am certainly not going to tell a name nor give it any more value than that! However if you take 6 months to complete an IR, something I know happened in one case, then the chances of a first-time pass are remote).
However, be wary of schools who over train all of their students just to get high pass rates. I don't know of that happening at the schools I know much about (really ETA (as opposed to EPTA), BCFT and PAT down here) but there have been complaints in this forum about this happening elsewhere.