The campaign was profitable Mon-Thu and bled out every weekend

The campaign was profitable Mon-Thu and bled out every weekend

The setup. B2B SaaS trial offer, search arbitrage, illustrative figures. Blended ROI hovered at break-even and I couldn't figure out why.

The move. Treated the campaign as one entity, adjusting bids on a weekly blended number that kept telling me "barely working, don't scale."

The numbers. When I finally split by day-of-week: Mon-Thu ran 1.45 ROI; Fri-Sun ran 0.52. B2B trials don't convert on weekends — nobody's signing up software on Saturday. Weekends were 40% of spend and ~15% of revenue, dragging the blended number to 1.01. The weekday business was genuinely great and I almost killed it.

The lesson. Blending across time hides the same way blending across geo does. A break-even campaign can be a stellar weekday business carrying a dead-weight weekend that should simply be turned off.

What I'd do differently. Dayparting isn't an advanced tactic, it's table stakes for any offer with a human-schedule conversion pattern. I now pull day-of-week and hour-of-day splits in week one. Killed the weekend spend, blended ROI jumped to 1.4 overnight — same campaign, just stopped buying traffic that couldn't convert.