Why your Discovery Insights
need an Expiration Date

​Dear Reader,​

"I believe we should split-test this change to the funnel."

"No, we tried that 3 years ago. Didn't work."

End of story...right?

9-ish years ago, I got to listen to Willem Isbrucker sharing his insights from running experiments at booking.com (famous for their quantitative data-first approach) at ProductTank Hamburg. Among other things, he discussed how split-test results had an expiration date. If I remember correctly, it was 6 months. Meaning, if you had an idea that was tested less than 6 months ago, it might not be worth retesting right now. But if it was more than 6 months ago, the changes that have occurred in the meantime justify re-testing.

Many people get hung up on how "horrible" booking.com's UI looks or how "6 months doesn't work for us." But I believe there's a more universal practice in that anecdote, that applies to you, no matter the industry, company size, or maturity: It's that what was true in the past might no longer be true because of context changes. In simpler terms, your insights could benefit from an expiration date.

In the context of Product Discovery, this doesn't necessarily mean you have to re-do generative research or evaluative testing every six months. What it means instead is to run planned decisions and activities through a mental checklist:

• Do we still want to understand/deliver for the same audience?
• Have our business priorities changed (i.e., what was engagement is now monetization)?
• Did the method we used in the past match the type of assumption we wanted to test?
• Do we now work with a different stakeholder group that can grasp a different type of data more easily?

Having researched or tested something in the past isn't a reason not to do it again, any more than it's a reason to start all over every time. What it is is an insight from a specific context you need to check for its applicability right now.

So, take this with you into your day:

What is an activity or decision you have recently dismissed because there was an effort around it in the past? How long was that ago? What has changed since then that might yield different, more actionable results?

Then, please reply to this email and let me know what came up for you.

Thank you for Practicing Product,

​Tim​

Join my In-Person Workshops in Berlin

I'm excited to bring my beloved in-person workshops back to Berlin in January 2026. You can choose between 1-day workshops on Product Strategy, Product OKRs, or Product ​Discovery, or opt for the full 3-day experience for you or your team.

(reach out for custom team quotes)

If you consume one thing this week, make it this...

Four Product Discovery Models: A Practical Map Read it here

Who is Tim Herbig?

As a Product Management Coach, I guide Product Teams to measure the real progress of their evidence-informed decisions.

I focus on better practices to connect the dots of Product Strategy, Product OKRs, and Product Discovery.