I can tell you whats real frustrating is when you have an upcoming checkride and you practice practice practice until your nailing the PTS down cold - then come checkride day you go up and make the stupidest little mistakes for no reason. There's just something about having that DPE next to you that scrambles your brain. Luckily they know that and take that into consideration when they are grading you. If you can use the same DPE for multiple rides you will get real comfortable with him and just fly the airplane