A single cross box with no return is not a good idea. It may help the guys who can't fly a straight line, but half the sequence will be drawn in too tight or pushed out to far for those flying the sequence properly.
I have to disagree CJ. A cross-box humpty can be made very tight over the top. 99% of the time when you pull vertical, you will be able to decide very quickly if going out or coming in is best for you. Now a 180 degree roller, figure-N...those are different animals. Cross-box humpty - no biggie.
Ken