In my opinion, the Kaplan full lengths are not indicative of your final MCAT score. However, some of the "free standing" questions may be relevant to what you need to know for the actual MCAT. Personally, I thought the Kaplan questions were harder than the ones on the real MCAT. However, Kaplan scoring was inflated compared to AAMC scoring. If I remember correctly, I would miss a handful of questions on a Kaplan section and receive the a certain score. Then, I would miss only two questions on a practice AAMC section and receive the same score. For me, the Kaplan practice sections were not at all indicative of how the real MCAT went. AAMC is the best gauge of how you're doing.