Why the same model performs better in 5-way 5-shot than 5-way 1-shot ?

[arcsinx11]

I really appreciate your original ideas in zhihu.When all the data can be chosen,5-shot can be better than 1-shot. 1-shot is easier than 5-shot to find the optimum weights,isn't it? So i think 1-shot can be better than 5-shot,but it not.Can you give me some advice?