My coach or mom always read for me when possible, why not?
I have been working on my problem with show nerves and trust me, no matter how many times you've practiced a test nerves can make you forget the entire thing. Hearing a familiar voice in the ring helped me calm down, and knowing I won't forget my test calmed my nerves a lot, just one less thing that could go wrong.
I definitely forgot my test once even with a reader though, when I'm riding I can't hear the reader at all I'm to focused, so I went off course with a reader, lol!
If there are no horses in heaven... im not going.