Every school is a little different. Not every school has a final "preceptorship" or "capstone" experience. However, more and more schools are requiring something along these lines as they seem to be good learning experiences that help prepare a new grad for the realities of the work world.
In my state, every RN program is required by the BON to include in the curriculum a final, "transition to practice"-type preceptorship before graduation. (I don't know, offhand, what the minimum number of hours required is, though.)