I am not "Roger," but I can recognize someone who has long and practical experience with managing metrics and KPIs and their interaction with process improvement. Instead of an "expiration date" I would encourage you to define a "re-evaluation date" that allows enough time to judge the impact and efficacy of the metrics proposed and make course corrections as needed (each with its own review dates).
Here is a quote to give you a flavor of his philosophy:
"A business should be run like an aquarium, where everybody can see what's going on--what's going in, what's moving around, what's coming out. That's the only way to make sure people understand what you're doing, and why, and have some input into deciding where you are going. Then, when the unexpected happens, they know how to react and react quickly. "
One good book on the positive impact of a metric that everyone on a team or organization understands is "The Great Game of Business" by Jack Stack https://www.amazon.com/Great-Game-Business-Expanded-Updated-... I reviewed it at https://www.skmurphy.com/blog/2010/03/19/the-business-is-eve...
Here is a quote to give you a flavor of his philosophy:
"A business should be run like an aquarium, where everybody can see what's going on--what's going in, what's moving around, what's coming out. That's the only way to make sure people understand what you're doing, and why, and have some input into deciding where you are going. Then, when the unexpected happens, they know how to react and react quickly. "
Jack Stack in "Great Game of Business."