Is sketching suitable for creating concepts?

Question

Design

I've been modeling for a while now. It seems that I'm not so bad at working with polygons, but for now the model is only based on references and drawings. If I'm going to do something on my own, it usually doesn't go very far. So I want to brush up on my concept art skills a bit. I really liked the sketching technique, but I don't know if it's suitable for creating concepts. There are no clear proportions and sizes, it's just drawing on the go. And I would also like to add that I will make concepts only for myself, that is, I do not need to make concepts so that other modelers can understand them. Well, I'm a schoolboy, so the ability to draw on paper without a computer is a plus for me.