3Fingeredglove is the real expert, but I believe the one year in residence (sit rule) APPLIES UNLESS an exception in the regulations comes into play. I am not familiar with D3 to D3 transfers, however, I know that it does apply D2 to D2, NAIA to D2. Transfers to NAIA are different, I believe they only require 16 weeks of residence.
The major exception is the first time transfer, with releases, and no conference prohibiitons, that allow this to take place.