I've never owned a pair of monk strap shoes, but I intend for this to change soon. Are the bukles on monk straps intended to be functional, in the sense that they are there to tighten or loosen the shoe, or are they pretty much just decoration? If they are meant to be functional, should the shoe fit so that it buckles at the middle hole? Has anyone ever had a problem with the hole getting stretched by the pressure from the buckle? Thanks, HS.