I just checked my Grizzly DRO and if the start angle and end angle are the same or differ by some multiple of 360º, (360º, 720º, etc.) the number of holes entered will be correct. However, if the end angle differs by even .001º. As an example, drilling a four hole bolt circle; center 0,0, diameter 2, start point 0º, end point 360º will put holes at -1,0; 0,-1; 1.0; and 0,1 However, entering 359.999º for the end point, the holes are located at -1,0; -.866,-.5; -.5,-.866; ans 0,-1.
To answer Bill's question about entering negative angles, the negative angle is converted to its positive equivalent. For example, drilling four holes between 0º and 90º, center 0,0, diameter 2, start point 0º, end point 90º, the holes are located at -1,0; -.5,.866; .5, .866. If the end point is -90º, it is internally converted to 270º and the holes are located at -1,0; 0,-1; 1.0; and 0,1.
This is on a 16 y.o. DRO, model nos. H6087 -H6098, running software version 8M-B