For either orthos or 3D, I think that you would do better with more than one flight path. The software needs images from different locations to properly triangulate the horizontal and vertical positions of key points in the images. For example, if you were mapping a winding road, pipeline, etc. you would probably want to fly offset of the centerline, on each side, to produce a good side overlap(70% or more) of the project site. It is much like resectioning a position with conventional ground survey equipment. The stronger your angles of your measurements, the higher the accuracy of the point you are computing. The number of flight lines you need depends on the width of your corridor and flight altitude. I have found that three or four, properly offset lines works well.