Klaviyo merchants: how do you decide the actual reorder window for win-back?

Question for merchants or in-house retention teams using Klaviyo with real store data:

Klaviyo can already do a lot of the segmentation work for one-time buyers.

What I'm trying to understand is the decision that comes before the segment:

How do you decide when a customer is actually overdue for a second purchase?

For stores with different product categories, do you already have reliable reorder windows by product/category?

Or does someone still have to manually analyze repeat-purchase cohorts and decide what "too early", "overdue" and "worth targeting" mean?

I'm especially interested in firsthand merchant experience.

If this is genuinely manual in your business, I'd be happy to test the logic on one anonymized example — no customer identities or account access needed.