Draw the relationship that prose makes hard to follow
A diagram is useful when the arrangement carries meaning, such as a sequence, a hierarchy or a feedback loop. Three labelled boxes can make an order clearer than a dense paragraph. The visual should explain a relationship rather than decorate a note that was already complete without it.
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Give the visual a specific task
A paragraph describes how a request moves from submission to review and then to one of two outcomes. A small branching diagram can make that structure visible at a glance.
Choose the diagram around the relationship. A sequence needs ordered stages; a hierarchy needs levels; a branching decision needs labelled alternatives.
The labels should be understandable without guessing what an arrow means. If the arrow represents approval rather than time, make that clear.
A visual does not automatically improve a note. Too many shapes, colours or decorative symbols can add work for the reader. Use it when seeing the arrangement helps explain something that becomes awkward or easy to lose in a sentence.