“Desk lamps” is a subject. It is not yet a useful article. Ask a more focused question—such as what to consider when choosing a lamp for a small desk—and the writer has a reader, a decision, and a reason to leave some details out.
Give the subject edges
A good question makes the boundaries visible. An article about choosing a desk lamp might cover footprint, adjustability, and where the light falls, while leaving the history of electric lighting for another time.
That limit is not a loss of depth. It is what lets the piece spend time on the details that matter to its particular reader, instead of trying to say everything about a broad topic.
Follow the reader’s decision
Before drafting, picture the moment that brought someone to the page. They may be measuring the clear space between a monitor and the edge of a desk, wondering whether a lamp base will fit. That concrete situation can guide which details come first.
When a paragraph no longer helps with the question, it may belong elsewhere. Keep the question close as you revise; it is a practical way to make an article feel considered rather than merely complete.