Go find yourself an old windscoop sometime and test your pickets. Place them and then you and a buddy or two try to pull them out. In summer snow, at least, I pretty well convinced myself that deadman style is WAY stronger.
For what its worth, the only conditions where I've ever really thought pickets placed in their "intended" position were something I actually wanted to depend on were where the snow is bullet hard - approaching neve - such as I've found on Mt Cook in NZ but not often around here.