V Prong Weed Guard Angle

[bazakwardz]

I was watching one of Puglisi's online videos showing how to tie the EP Permit Fly. He tied in a V-shaped piece of mono just behind the hook eye for a weed guard. He said it was important to make the prongs stick out perpendicular to the hook, instead of sloped back towards the hook point. But he didn't explain why.

I always thought that the guard should be sloped back at about a 45 degree angle. I thought this would allow the fly to slither through the grass better without collecting vegetation. I also assumed it would cause less interference when hooking the fish. Which angle do you prefer, and why?