My daughter is 9 and in the summer although she loves gymnastics, she sometimes has a hard time with going once a day! She is fine when she gets there and as I said loves gymnastics, but summer should be time for some fun too! She only goes 4 days a week and mostly 4 hour days and she is SO excited for her "day off" so she can do the normal fun summer stuff. I think twice a day is crazy for a 6 year old of any level. Even once a day for 3 or 4 hours is a lot of work and you want her to have some time for fun stuff or she is going to burn out quickly and want to quit all together. Hope you can work this out with your coach but if not do not doubt yourself.