I've never noticed it being an issue. Once in a while my LQS throws in an extra inch or two for something else (last time it was because mine was the first tear), but normally not.
I seriously have not seen this distortion and raveling everyone has talked about. Dampen and press - done. Since 1/4" is in the seam allowance I guess I just don't fuss if the edge is a little more ragged than it would have been with a rotary cutter.