I tend to run the grain with the longest dimension of the pattern. Example if the cutting is 8" x 10", I make sure that the grain runs in the 10" direction. It is not for strength, it just looks better to me. I doubt that a pattern would be any stronger or less apt to break regardless of grain direction on most cuttings.
It doesn't matter if the grain is vertical or horizontal it can still crack almost anyplace in the cutting but, I just think for aesthetic value it looks better in the longer dimension.
Rog