They do them in the morning and the afternoon so it depends but they are scheduled for approximately 30 minutes, from 10:00 to 11:15 with 15 minutes in between. I can't say for the afternoon but it follows a similar format beginning at 1 or so.
As a practiced gunner I must tell you that I missed lunch because of the engaging conversations I had during my interviews and I ate lunch with the Chairman of the Board of Regents for UT, instead. Talk was pretty light but centered around what I thought about Ohio State.
Michael DeBakey caught me walking in front of Baylor and asked me for dinner at his home in Rice Village it went very well and I expect an acceptance from Baylor and UT-H both. I will likely pursue my MD at Baylor and my Ph. D. at UT-Houston.

Sorry, I am in a weird mood.