Writing in this form is a merciless way to spot the holes, the disconnections in your understanding. Serious note takers call these permanent notes.

The process of writing in this mean should feel effortful, but on the same time playful. It is effortful because you deliberately filling the gaps and establish meaningful connection to your existing ideas and mental model. It is playful before in doing that, you discover new insights, new ideas.

The objective of this writing is so that you in the future, read these notes should still able to comprehend and not feeling banal. Not or poorly meeting this objective would leave your bar to concretize the idea too low to able to really comprehend the subject. Hence, why write to understand should equate to write to transfer for you future self or others.

Write to understand has a mutual relationship with Read with intention. "To write" gives a purpose to "to read".