You know that five-year-old (or older) Pantone book? It’s junk. Colours fade, even if you’ve been really careful. Sure, these books are really expensive, but not as expensive as replacing an order because you are a shade off and don’t know it. At a minimum, replace these once every two years. You need a new one just to keep up and be relevant.
(See Images Printed & Digital Editions for regular words of wisdom from Marshall.)