Tweeters, thanks for your post. Did your coach have you move back to a spot you felt comfortable as soon as you didn't go for it, or did you get a few tries first?
It depends on the day. Generally, I know when I'm having a scared day and will say what I need. Example: "Coach, I'm scared today. Will you please spot my first one?" or "I'm feeling nervous today, can I do my second pass onto the resi in my routine?" Sometimes he says yes and sometimes he says no, but he always has a reason and will share that reason with me if I ask.
When the issue first started cropping up I was really frustrated and wasn't sure how to tell him about my fear. He doesn't really like talking a lot, so I didn't want to get into a long conversation. So I didn't go for one of my tumbling passes a couple times in a row and then he stopped me and told me I had no choice but to go backwards a step, even though I was trying to convince him that he should give me one more chance. The truth is, I WANTED to try it again, but I'm not sure I actually would have done it on that 3rd try. It's a credit to my coach that he was able to read that from me and make the right decision. Like I said before, not something I believe you can teach, but a very valuable skill to have as a coach.
Anyway, if I were in the situation you described I would tell the girl her assignment for that day, and if she balks once, tell her she has one more shot. If she balks again, send her back to what she will do. Actually though, I'd give her the two shots and then I'd send her back to something you are absolutely positive she will do the first time, not necessarily the skill preceding the one she balked on.
It might go something like this:
Suzy balks on RO BHS 1/1 one time.
You say, "Suzy, you have one more chance to go for your full." (Don't tell her what she will be sent back to. As weird as it sounds, she could "decide" at that moment that she'll be scared of that skill as well).
Suzy balks on 1/1 a second time.
You say, "Suzy, I want you to do 5 RO BHS BTs, then come talk to me."
You see how that goes. If she's doing well on that, send her to do 5 layouts. Then you give her a choice- 5 fulls on tumble track/into pit/onto resi or 5 fulls on the floor. Let it totally be her choice. Don't encourage her one way or another and let her feel the success of completing that assignment. Then move on to whatever else she has to do.
The next time, you have to remember her disposition the last time and make a decision as to whether you start her out at a comfort spot for her (onto the resi, tumble trak, etc.) or whether her confidence indicates she's capable of doing a "normal" assignment.
While it's okay to show disappointment, I think it's also important to move on from that if there's a day that doesn't go well. She has to know that you support her, but will not let either you or her be manipulated by her fear. Both of you are in control, and can turn a bad day into a day with some level of success.
I hope that helps, and sorry I got so long-winded!