Enumeration is not running every available source. It is reducing uncertainty about a surface through questions that can be answered with evidence.
Form the question
A good hypothesis connects an asset, a condition and a consequence. For example: “a published service may expose a trust boundary between two environments”.
Choose signals
Select sources according to their ability to confirm or reject the hypothesis. Prefer low-impact observations and record negative results as well.
Stop at the right time
Define what evidence will be sufficient before starting. This prevents collection from expanding after the question has already been answered.