I don't think the same would really apply to piano performance. The reason you became shaky and nervous as you progressed was because you had more to lose. In the beginning, if you would have knocked your structure down, it wouldn't have mattered much, because if wouldn't have taken long to rebuild. But after, say, 20 minutes of work, you're going to become nervous due to the fact that if you accidently destroy your structure, it will take a lot more work to rebuild it. In piano, if you make a mistake in the middle of the piece, the good work you did previously won't be destroyed. I think it's always important to remember this when playing for an audience - it may help with nerves.