reasonable amount of time (she should not need to use too much extra time), but still does not get good scores, it is good sign that she either does not enjoy it or is not good at it, even though that is against your wish. making crafts and selling them are much much more intereting/important/valuable than being good at math, in my opinion.
I always believe my son is very smart. He has done great in math class, and obtained good socre on ACT test as a 7th grader. However, when he went to math tournament, I realize there several kids in this city that are so good at math, and my son will have very slim chance to pass them. So we just let him quitting on math tournament. He can spend the time on something else, which he is truly good at.
Math is important, but neither essential nor sufficient. Not good at math does not mean he/she is not smart; he/she may be just good at something else.