Nuancing a drawing or adding detail to it comes at the last stage. It doesn’t have to ofcourse, you could start a drawing with the details as many people do. The reason why so many people draw in the details straight away is because that’s what they see. It is a discipline to disregard the details and simplify what you see into simpler forms. As children we tend to draw the details we see and forget about proportions and relationships.
My daughter has done just that with her drawing of a young girl. It’s a lovely drawing and the proportional accuracy of the girl is near enough to not warrant criticism. My daughter clearly has an eye for detail but not enough discipline to lay down a proportionally accurate framework upon which to build the detail.
I also drew a picture of the young girl in the reference but I used a three stage process working from big to small blocks. I wouldn’t say my drawing is better than my daughter’s, they are different and there are a number of things I prefer in my daughter’s drawing. However if your intention is to draw closer to life, closer to what you see in real life, then it would be a good idea to adopt a process. I recommend laying down a framework made up of the largest divisions of space. Get these large and medium sized blocks proportionally correct then all the smaller details will just fall into place.