Can girls reward themselves 10 times a day?

Much better. First of all, rewarding yourself must be because you have done better in some aspects, so you will reward yourself. This will not only help you build up confidence in handling things, but also motivate yourself to overcome difficulties. Secondly, rewarding yourself is not necessarily a material reward, maybe it is a sentence, maybe it is a delicious meal cooked by yourself, and so on. These can all be regarded as rewards for themselves.