“The engineers at Google are always like '20% — no more than 20% in any given day on bids and budgets up or down.' I got burned pushing it more, and what happens is the system goes crazy. I only adjust by 20% every two to three days, not every single day, otherwise it keeps kicking back into learning mode at too great a frequency.”

Scale UAC budget max 20% every 2-3 days — not daily — or the algorithm goes rogue

Google's UAC algorithm treats large budget jumps as a signal to re-explore the entire inventory landscape, throwing it back into learning phase and tanking short-term performance. The 20% rule is an internal Google engineering guideline that Black could share only after leaving. Two-to-three day spacing between changes further stabilizes cohort comparisons.