The additional water flow from the hip (valley) of my roof would sometimes overrun my screen gutter covers. I made this thing to slow down the water so it can flow into the gutters.

It clips on to standard K-style gutters. I use Amerimax snap-in filter gutter guards, which I cut a notch into to allow the hip shield to snap into place. These pieces have a shelf that the filters can rest on top of instead.