Why seasonal campaigns need a different measurement window

A seasonal or holiday campaign gets evaluated, by default, using the same weekly performance cadence a business applies to its evergreen, always-on campaigns, and that default routinely produces a misleading read, because seasonal purchase behavior doesn't distribute evenly across a campaign's flight the way evergreen demand does.

The distortion shows up specifically in early performance: a holiday campaign launched three weeks before the peak buying window will, almost by definition, show worse CAC in its first week than an evergreen campaign, not because the campaign is underperforming but because it's running during the awareness-building phase of a purchase cycle that hasn't reached its actual conversion window yet.

The measurement window that actually reflects a seasonal campaign's performance evaluates the whole flight against the whole period's aggregate result, not week-by-week against an evergreen benchmark, and separately tracks a leading indicator, like add-to-cart or wishlist activity, that can signal early whether the campaign is on track before the actual peak conversion window arrives.

Judging a seasonal campaign's early weeks by evergreen standards is one of the more common reasons a genuinely on-track holiday campaign gets prematurely paused or reworked, precisely during the awareness-building phase it needed to succeed at the peak.