We do vault by vault height. I have no idea what the main bar coach does, but when I set the order it is random. Floor is also random. For beam, I start with the gymnasts I believe are the most likely to stick and work my way down to the least consistent with the hope that staying on the beam will be contagious. I do not believe that the order has any impact on score. I also like them to get used to competing in different spots because for State and Regionals the order is pre-set.