As an aside, do strongly consider why you are going on a second look and what you want out of it. They are a pain for programs because people have to go out their way to make time to see you on an occasion scheduled just for you and whilst most places will be happy to do so, rarely is it going to be helpful in actually informing your decision of where you want to go. Possible reasons for going on a second look are to meet with a faculty member who you are interested in working with and who was not available before, to meet with residents if you did not get an opportunity to when interviewing (which is a red flag in itself), to visit a site where you will do much of your training that you did not get to visit.
You should not go on a second look to show how interested you are in a program, or because you think that it will help how highly you are ranked, because it won't. The other caveat is the whole interview trail is a dog-and-pony show, everyone is doing their best to be enthusiastic and by the end you will be burnt out. The more contact you have with the program the more likely something negative will happen that may cast you in a bad light!