Why do artists often paint realistic pieces chunk by chunk instead of in layers of detail?

Question

Sorry if this makes no sense at all, I am in no way an artist. I often see WIPs of realistic portraits where the artists tend to draw section by section as opposed to starting with lines, then colours, shading/highlights, etc. I just can’t imagine how this is practical or even possible.

In: Other

Answer 1

I think if you’re leaning towards the hyper-realistic portraits then they may go by grid work. Detail and color for each block/grid piece. If they’re using a photo for reference.