U don't need to flash constantly, if you are holding stuff in Stone Vigil then you is probably fine. Flash is just good initial aggro because its 360 degrees, I would toss it in between a halone combo every now and then to make sure you keep aggro up on the mobs you arn't attacking. That way the healer doesn't get aggro or some dps who decides to randomly hit something doesn't grab it.

Don't forget Circle of Scorn cause that ability is amazing. <3 paladins