Greg scouted a ton of fun controls, so I've got plenty to choose from in making the final course.
What's preventing you from using all of them? Maybe people might enjoy a super high density Scramble?
I'll answer here! Turns out that 32-34 controls is perfect for assigning point values to controls if you want a total of 1000 points possible. With say, 40 controls, you'd need to number them so:
... with no 50-pointers. Hey, though, that would be OK, I guess! Couldn't go over 40 controls.
OK, here's the other thing: fitting all the questions on a piece of paper 8.5" wide. I think that's the major constraint.