When teaching developmentally, one takes into consideration the child as an individual. Teaching and learning are much easier for a child when they are developmentally ready.
One can approach education from a curriculum based teaching approach or a mastery based teaching and learning approach.
Most schools are curriculum focused rather than mastery focused. Knowledge has been divided into 13 tidy units (grades k-12) to be drip fed to children each year whether they are ready developmentally or not. This makes for efficiency in teaching and grading, but is not the most effective way to learn.
A true mastery approach to learning is founded on a child learning when the child is developmentally ready to learn. While one can hinder, distract, or delay development, one cannot force the brain to develop.
I invite you to share your thoughts below on curriculum vs developmental teaching.