occasionally way off - why?

[nchunter]

I went to a 3-D shoot on Saturday.  Toward the end of the course I had a few errant shots that were way off the mark.  Usually I'm pretty well on target lef-to-right, and when I miss it's due to elevation.  

But all of these shots were at least a foot high and a whopping two feet to the right!

What defect in my form or release would cause way high and to the right?

[Molson]

Sounds like your bow or release arm collapsed.  Probably just fatigue if it came on at the end of the course.

[Orion]

If you didn't bend an arrow, probably just got tired, losing concentration and form.  Few people shoot an entire 3-D course well.  Most have a letdown of several targets or more sometime during the shoot.