The Creative Decay Curve:
Detect Fatigue Before the Spike.

No creative lasts forever. The question is not whether your top-performing ad will decay — it's whether you'll catch the decay before it costs you. Most growth teams are managing creative fatigue reactively: CPA spikes, they investigate, identify the creative as stale, and scramble for replacements. This reactive loop typically wastes 7–14 days of budget. The brands that win the creative game manage decay proactively.

The Decay Timeline: 4 Stages

1. Launch Phase (Days 1–7): CTR climbs as the algorithm finds the highest-fit audience. CPA is at its lowest. ROAS peaks. This is the scale window — increase budget here.
2. Peak Phase (Days 7–21): CTR stabilises. Frequency builds across the retargeting pool. CPA stable but slightly elevated. Continue scaling with caution.
3. Decay Signal (Days 21–30): CTR declines 5–10% week-over-week. Frequency hits 3.0–4.0 in core segments. CPA still acceptable but trajectory is downward. This is your action window.
4. Fatigue Phase (Days 30+): CTR has fallen 25%+ from peak. Frequency above 5.0. CPA spiked 30–50% above launch. The algorithm struggles to find new buyers at cost.

The Decay Detection Formula

Monitor this ratio daily: (Current 7-day CTR) ÷ (Launch 7-day CTR). When this ratio falls below 0.75 — combined with Frequency above 3.5 — initiate creative rotation. This signal consistently appears 5–10 days before CPA spikes, giving you time to respond without crisis urgency.

Building a Proactive Creative Velocity Engine

1. Maintain a 15–20% testing budget. Run 3–5 new creative variants per week at $30–$50/day each. Always have a tested replacement before you need it.
2. Use a winner stack architecture. Keep your top 3 proven performers running simultaneously. When the oldest decays past threshold, retire it and promote the newest winner from your test pool.
3. Diversify formats. Static images fatigue faster than video. UGC tends to have longer decay cycles than brand-produced content. A mixed format portfolio extends your overall creative life by 30–40%.
4. Separate message rotation from format rotation. Before retiring a concept, test a message angle change on the same format. Updating the opening 3 seconds of a video or the headline of a static can extend peak performance by 1–2 additional weeks.