i wish someone else would reply to give their impression of it...
maybe a little more than 10%...id assume that just to be careful. like i said, im pretty sure that i learned some important reactions the first 3 weeks of orgo 2 that i thought were helpful. i used kaplan and barrons and then also had a friend's books from the kaplan review course. to study i went though and outlined the orgo chapters in the HUGE kaplan review book that they give you in the kaplan course and then memorized and did practice problems. between those i thought that the reviews did a pretty good job of preparing me (plus my previous knowledge of orgo of course). the orgo section is pretty general, i feel like kaplan does very good prep for it (in comparison with QR and PAT..which i do not think the kaplan stuff prepared me for).
but overall-yes, study your orgo 1 stuff like crazy...know some of the big reactions in orgo 2 and i wouldnt worry so much about orgo 2 stuff like carbohydrates, etc.