since this is all so new to me, and since i am the type of guy who learns best by doing and seeing, and since my new bench is not flat where i edge-glued the 2x4s, i thought, what the heck?
so i decided to try using the transitional plane with the non-rounded blade, going across the grain at about 45* or so, just to see what happens.
i see the edge lines you all are referring to, and what the smoothing plane would be good for. this bench will be flat when i'm done with it! then I will put some lindseed or danish oil on it to seal it.