For the average person, every other day, or every 2 to 3 days, without washing is generally fine. There is no blanket recommendation. If hair is visibly oily, the scalp is itching, or there's flaking due to dirt, those are signs it's time to shampoo.
But for your hair to look beautiful it is not enough to just wash it, you should also use other hair care products, such as curly hair serum.
With this serum, you can improve the appearance of your curly hair and it will no longer split and so on.