The question really is, “do the targets change angles randomly or do you program each shot for a change? I.e. hard right from station 5 is thrown until you change the program to throw a straight a way station 5, or does it change angles after each shot from station 5?”
It does what the rule book says! (And what Trap shooters in the USA have said when they helped us develop the layout!)
Rule K: “A trap machine which throws targets at an unknown angle shall be used.”
In our implementation the trap changes angle (within the limits permitted) after each shot you take. If you do not fire it counts as a “No bird” and you can shoot at the same angle again.
For doubles it is different – the trap angles are fixed (Rule N). Our system has one target spot, so for doubles it shows the first clay until you hit it, then it carries on with the flight of the second. In the case of ATA Trap Doubles it releases the right bird first for posts 1-3 and the left bird first for posts 4-5. This seems to be the way that most ATA shooters take the clays.
DryFire is infinitely flexible – if someone wants a layout which works in a slightly different way (like locking the angles until you press a screen button or something) then you will want to try the “ATA Fixed” layout.