The people most tired of an identity are the ones who see it every day at nine in the morning. They are not the audience, and their fatigue is not a brief.
A refresh is usually proposed by someone new, in a role that needs a first project. The current mark is called dated. Nobody asks whether the audience has noticed, because the audience is not in the room.
Separate drift from age
An identity that has drifted looks inconsistent: six spine treatments, four arrow styles, three versions of a blue. An identity that is simply old looks consistent and unfashionable. These are opposite problems and only one of them is expensive.
Drift is repaired by writing rules and applying them to what exists. That work is unglamorous, invisible in a case study, and almost always the right answer.
Drift and age look alike from inside and cost nothing alike.
Count what you would throw away
Forty years of a backlist is recognition you cannot buy and cannot rebuild. Before redrawing the mark, price the shelf: every spine, every reprint, every bookseller who shelves by publisher.
On the press we respined two hundred and twenty titles and left the mark alone. The shelf read as one publisher for the first time in a decade, and no one had to be told about a rebrand.
Refresh when the market moved
There are real triggers: a merger, a new category, a name that cannot be registered where you are going next. Each is a fact you can point at, and each survives a change of marketing director.
Boredom is not on that list. Write the trigger down before the work starts, and the work stays honest when the person who commissioned it leaves.