custom_label_3

`custom_label_3` is most often used for promotional or campaign-specific flags — short-lived tags that ride with a specific campaign and get cleared when the campaign ends. Black Friday 2026, holiday gifting, end-of-line clearance, new arrival promo — each gets its own value, and the product set rule for that campaign matches the value.

The discipline here is cleaning up after promotions end. A catalog accumulating `bf2024`, `bf2025`, `bf2026` tags over the years carries dead segmentation data forever. Set a quarterly review where expired campaign tags get cleared. Most accounts find their custom labels are 60% stale within 18 months — the cleanup keeps the segmentation surface clean and the rule logic interpretable.

For longer-running promotions (loyalty programmes, ongoing subscriber discounts), this slot still works but consider whether `promotion_id` (which links to an account-level promotion definition) is the better fit. `promotion_id` carries dates and discount mechanics; `custom_label_3` carries just the membership flag.