Holds for trap:
Station 3 - Hold just off center of the house (right if you're a righty or left if you're a lefty)
Stations 2 & 4 - Bisect the middle and the front corner of the house on your side
Stations 1 & 5 - 3-5 yards off the front corner, left on 1, right on 5
If the wind is behind you hold low on the house.
If the wind is in your face hold high on the house.
Most acute rock angle is hard left on station 1 or hard right on station 5.
Toughest rock for me being a righty is hard right on station 5. My right arm is in the way of a fast/smooth swing and in a blink I'm behind it.
What I was taught is slightly drop your barrel, catch up to the rock with the swing, then bring the barrel back up in front of the rock as you squeeze the trigger.
It looks like snap shooting - it is NOT!