I have been scheduled for an onsite interview at facebook for ios. I see that usually the interviews are 4-5 hours long, mine is 6 hours long with two design questions (usually one system design question is asked). I was under the impression I was going for an E4. Does anyone know if this is now the onsite circuit for an E4 or is this for a different level? I asked my recruiter but I have yet to get clarification.