I asked that very question the night before the moderators yanked the thread that it was on, a Dr. Longshot brawl as I recall. Here is what Tachyon responded:
"Old Winchester hand set traps (when we started trap six had a hand set trap which required someone in the house to put a clay on the arm for each target... had to be fast) had a plate with holes in it. If you put the peg in the third hole then the trap would oscillate from about 50 degrees right and 50 degrees left. The arm had a drop arm which would hit the peg and change directions. If you put it in the second hole then the angle was less (about 43 degrees). On a three hole setting post one would get a straight away on a hard right and post 5 would get a straight away on a hard left. If you got a hard right on post 5 you had to lead the bird like a skeet target on post 3. In other words the angles are less with 2 hole targets than 3 hole targets.
The other issue with the Winchester traps was that you could "read" the trap. it would oscillate in a predictable way from left to right. If you shot a lot of trap you could get a beat going where everyone would get a straight away from the post you were shooting at every time. A lot of 5 people shooting 500 straight resulted. eventually they changed the rule to put in an "interrupter" which would interrupt the oscillation at a random time making it impossible to 'read" the trap. "
The Turret on the western traps had numbers 1-5 the higher the number the more extreme the angles. Meaning the 5 hole would throw targets so wide it was possible for the target to clip the edge of the trap house when leaving the machine.
I believe it's legal to throw the same "3 hole" angles at any ATA event even today. It's just that most clubs opt not to do it. So, on average, today's angles aren't quite as extreme but now you can't read the traps, so what's the big difference? I think higher scores has more to do with shells, better dissemination of knowledge, and adjustable guns. But even if the targets are easier, it doesn't make much difference in the end. I mean after all, if they're so damn easy then simply don't miss any and nobody can ever beat you.
In short, the subject of 3-Hole targets is just something for old has-beens to whine about.
If you look at the center of the machine, you will see a round flat surface that has another object secured to it with a screw in pin. That round flat surface spins. There are several numbered holes in the round flat surface. The hole that you choose to use with the screw in pin determines the width of the angles.
None of this matters though since these traps have been obsolete since the early 90's.
I spent countless hours sitting next to one of those. I could keep up with the fastest squads in my mispent youth. The secret was to have the case of birds open and the dividers pulled out. I don't remember ever having to set doubles though.
And here all this time I thot they were talking about those targets you find w/3 holes in them that didn't break! I've seen some with more holes than that in them too, but I don't see much discussion about those. Hahahaha
Are wider angles tougher? Sure they are.
The bigger issue from my perspective, is the lack of places to shoot ATA targets routinely today vs. a few years ago. Was a time I could shoot ATA once a month at one nearby club year round. Today that club is long gone & there are only two clubs throwing ATA targets anywhere near & they only do so in the warmer months & one of them only has an ATA shoot twice a year. OTOH, there are many more nearby places to shoot registered skeet or sporty clays, both of which tend to be more expensive to shoot in their registered formats. It is a less than subtle message, IMHO. I'd like to see trap as it once was as much as the next guy, but its going to be a hard row to hoe unless we start introducing more people to the sport. I simply don't see the numbers that I used to at the local ATA shoots.