Build a collection around a question
A collection becomes easier to use when it serves a purpose narrower than an entire subject. Better writing can hold almost anything. How to explain a difficult idea gives each note a role, such as defining terms, arranging steps or choosing an example that makes the explanation concrete.
Go deeper
Give the collection a reason to exist
A folder called communication can grow indefinitely without helping its reader decide where to begin. A collection answering how to explain a difficult idea has a clearer destination.
A question-based collection gives individual notes a shared purpose. Each note should contribute part of the answer rather than merely mention the same broad subject.
The collection can include a short introduction that states who it is for and what the reader should understand by the end. Notes that do not serve that purpose can remain elsewhere without being deleted.
This approach also exposes missing pieces. If the collection explains how to begin but never how to check whether the explanation is understandable, the gap becomes visible against the question it promises to answer.