I think that it is very program dependent. Don't hesitate to email programs that you are interested in and get their feedback on what they think about 2 weekers. I initially tried to do a 2 week rotation, contacted a couple of programs, but decided not to later. 1 of the 2 approved it. I had a friend do 2 weeks at Cincinnati, another do 2 weeks at Geisenger, another do 2 weeks at Toledo. Another applicant I know did three 2 week rotations and got interviews at all three places. I seems that the more academic programs don't allow it. But I think it is worth showing your interest and getting your name out there too. Just be careful to not burn any bridges.
