Increasing Google Ads spend before tracking is solid is the single most common reason performance regresses after scale. The bidding engine optimises toward the signal you give it; weak or missing signal makes the model worse, not better.
Conversion tracking, in priority order
- 1Primary conversion actions defined and only key actions marked as primary.
- 2Enhanced Conversions enabled to recover signal lost to cookie restrictions.
- 3Consent Mode v2 implemented for users in the EEA, with the new ad_user_data and ad_personalization signals wired up.
- 4Server-side tagging via Google Tag Manager where the data layer warrants it.
Why Smart Bidding needs clean data
Google Ads documentation states that Smart Bidding uses auction-time signals together with your conversion data to set bids per query. If a portion of conversions never reach the platform, the model under-bids for the audiences that actually convert. Enhanced Conversions exists specifically to send hashed first-party data back to Google when the standard tag cannot fire.
Consent Mode v2 is non-negotiable in the EEA
Since March 2024 Google requires Consent Mode v2 for advertisers using measurement, remarketing, and personalisation features for EEA users. Without it, audience lists cannot grow from EEA traffic and conversion modelling is unavailable for those users.
Conversions match CRM within an acceptable variance for the last 30 days, Enhanced Conversions diagnostic shows healthy match rate, and Consent Mode signals are reaching the platform.
Where this is drawn from.
This article references the following publicly available documentation. Always verify against the original source — platform features change frequently.