Mistake: cost entered manually, never updated

Mistake: cost entered manually, never updated

Failure mode: you type campaign cost into the tracker once at launch. The source adjusts bids, dayparting shifts real spend, and your ROI dashboard runs on a stale number you forgot you set.

Fix — 5 steps:
— Use automatic cost integration where the source supports it: API pull (Facebook, Google) or cost tokens in the click URL.
— For sources without an API, pass cost-per-click via a token ({cpc}, {cost}) so each click carries its real price.
— If you must enter cost manually, schedule a fixed daily reconciliation against the source billing screen — make it a recurring task, not a memory.
— Flag any campaign where tracker spend and source spend diverge by more than 5%.
— Lock down who can edit cost fields; accidental overwrites poison historical ROI.

Verify: pick one campaign, compare tracker spend to the source's billing for the same window. They must match within rounding.

Save this SOP. Run this before every launch.