when i interviewed at USC, the second day was only an opportunity to observe a PBL session, it was not mandatory for the interviewing students.
The PBL sessions that week were canceled for some reason, so I did not go and observe.
Also, the individual interview with a faculty was only mandatory for second-time applicant to USC.
Firt time applicant can also request an individual interview with a faculty, but the dates were not available for about a month later, which i thought would totally delay my application, so I opted not to do it. And the administrators also did not recommend it for first time applicants for whatever reason.
anyhow, good luck on your interview.