All they are allowed to say is "yes, that you have an interview" or "your file is being reviewed". They can't tell you anything about being accepted until Dec 1st by law. Even after Dec 1st they can not tell you that you have been rejected until all of the seats have been filled. I was told that after Dec 1st they can offer you a hint like, "you might be better off accepting an offer from another school if you have one", but can't say much else.
The ADEA has stats on this. If you do a search on SDN you can find that info posted someplace too. I think for the Texas schools I saw an average of 300 interviews per school. That seems about right because I interviewed with 14 people; interviews started in Aug going through Dec or later; about 18-20 weeks at 14 each week equals 280ish…
Once they confirm acceptance of all avail seats then they mail rejections letters; usually around March or April.
They keep doing interviews as late as February according to post on SDN from last year. I don't know if this is true because it doesn't make sense to keep interviewing after Dec 1st in my mind. They have already looked at 200+ possible good candidates by Dec 1st, so why add more to the pool after the first acceptance deadline?
Hypothetical scenario...
Every school has 200+ good candidates to potentially accept December 1st. Those same 200 candidates could be accepted to multiple schools. So, as these candidates choose different schools to attend, the pool of 200+ good candidates gets smaller, so they interview more students.
Schools also take into account that applicants who have been accepted to multiple schools, will accept multiple offers, and hold their spot at 2 or 3 schools. Fair? Not really. But that is why they continue to interview.
Schools such as San Antonio and Baylor and other state schools will also interview a small number of out-of-state applicants. Not every out-of-state applicant who gets accepted will choose to attend that particular school if they have more than one offer.
Another example... Student A has interviewed at all 3 Texas schools. Student A really wants to go to San Antonio. Come December 1st, Student A is accepted to Baylor and Houston, but not San Antonio. Student A holds a spot at Baylor or Houston. Come February, Student A gets accepted to San Antonio, so they drop their place at one of the other schools. If Baylor or Houston had quit interviewing people, then the decision of Student A to attend San Antonio, would have left an empty spot in their class. It doesn't seem like a big deal with only one empty seat, but this happens all the time with multiple students, so schools continue to interview.
Also, I know someone who was accepted to all 3 Texas schools on December 1st. She held her spot at one of the schools. She interviewed at an out-of-state school in January. She got accepted to this school in early February, and chose to go there. So, a seat opened up at where she was holding a spot. This sorta thing happens quite a bit too.
Some schools will continue to interview because they don't feel like they have the pool of candidates from which they want to accept their entire class, so they continue to interview. It can become a really good thing for those qualified applicants who submitted late for whatever reason.
