The angle is not of great significance, except for your personal preference. Much of your regrowth will come from sprouts at the heel.
Plant density on a young maiden hedge like that has no effect on the angle, purely how hard you push it down.
Older, heavier hedge you would need to thin hard to get it low.
Just finished length of hedge on farm, 150 years old roughly, been laid at least once but not for 60 years.
Crab apple was quite a challenge, laid low to encourage maximum new growth from stump.