The oud and the guitar are strung similarly (six strings vs. six courses of strings), and are both played with a flat pick; but the guitar pick is much smaller and flatter than the risha used for the oud. Did the different picks for the different instruments evolve by accident, or is the oud somehow better suited to playing with a risha and the guitar better suited to the triangular guitar pick? Could you reasonably play a guitar with a risha, or vice versa?