Smart Bidding is Google Ads' family of automated bidding strategies (Target ROAS, Target CPA, Maximize Conversions, Maximize Conversion Value) where the algorithm sets bids in real time per auction, using signals the advertiser cannot see directly: device, time, location, audience signals, query intent, conversion likelihood.
Manual CPC at enterprise scale is an anti-pattern -- the algorithm has more data than any human team. The governance question is which Smart Bidding mode + which signal-quality posture per campaign. Target ROAS or Target CPA needs roughly 30 conversions per 30 days for the algorithm to perform well; below that, Maximize Conversions / Maximize Conversion Value is the starting choice.
The discipline: Portfolio Bid Strategies group brand-line campaigns sharing a target, Seasonality Adjustments handle known event spikes (BFCM, Diwali, EOSS), Data Exclusions handle known measurement gaps, and the conversion-data integrity stack underneath (Enhanced Conversions + CAPI + offline-warehouse) feeds the algorithm a clean signal.