I know that 12, 16, and 18 plus probably a few others have traditional 4th round locations, but except for those, who gets to pick the hole locations for the Masters? And is there a scoring range against he/they are operating?
Most of the hole locations are more or less the same each year, but they mix it up a bit in terms of which one to use on which day. For example, the hole location where Nicklaus holed his long putt on 16 on Sunday in 1975, was the Friday hole location this year, discounting the fact that the green has been rebuilt twice since then.
On 17, some years it is back right on the shelf on Sunday, like this year or in '86, and some years it is tight to the bunker, which they used for the Saturday round this time.
On 18, it's almost always front left on Sunday, but they have used the back pins on occasion. The back right pin that they used Saturday is a relatively new one created by recontouring the green a few years ago . . . as is the top left hole location on 14.
I was once told they have the hole locations figured out down to the nearest foot, so if they want it to play a little harder than normal, they know where to shift the hole location by a foot or two so that fewer putts are holed, based on their historical data. That's what you can do if you host a tournament every year for decades.