I thought this was a pretty slick way of doing it, and it's how I was taught too...
http://www.finehomebuilding.com/2016/12 ... ng-eletterBut I think I found a better way...
Instead of all those complicated jigs and such, I just make an auxiliary fence that matches the drop on the wall. When I put the piece on the saw, I just make sure it's flush with the top of the fence, and it's perfect.
But, sometimes, there are times when I might not hold it flush with the top of that fence. It all depends on the particular corner... and the mudwork... ect...
Coping the inside corners is always foolproof, but, cutting actual bevels is much faster "if you can get it done on the first try"... I have a friend who bought an expensive tool to figure out the exact angle, and I'm sure it's as slick as can be, but I don't have that tool. ... I was taught how to to do it with shims and pencils, and a framing square.... and skill in the eye... but my eyes ain't quite as keen as they used to be... but the skill is still there..
I hate having to wear glasses...