For declarative speech, consider the listener's presumed state before judging the value of emphasis. For non-declarative speech, identify the form and then ask whether it makes a literal request or performs another rhetorical function.
For fronting, analyze syntax and context; for restriction, specify the construction and its scope; for omission, explain the clue and resulting effect. Joining and separating clauses depend on their relation, while brevity and expansion depend on whether they communicate effectively.
A sound answer explains the reason for the form, not only its category.