somewhere between week 6 and week 10 of your 100-day run, your reply rate will drop, probably by half.

if you don't know why it dropped, you'll panic and swap copy, lists, providers, and everything else at once. that's the trap most teams fall into, and it's exactly why they restart from scratch every 3 months instead of running a 100-day playbook cleanly through to the end.

THE REAL SYMPTOM

i spoke to an agency owner recently whose reply rate had dropped from 5% to sub 1% over the course of two months. he was certain it was the infrastructure and he asked me to audit it.

my first question was when he'd last changed his hook line or primary angle. his answer was "i haven't really."

that answer is copy fatigue summed up in a single sentence.

his exact case: he was working in the TikTok shop space, connecting brands with affiliates to go live for products. a year ago, that approach was cutting edge and nobody was doing it at scale. today everybody knows to use affiliates on TikTok shop and get them to go live. the hook line stopped working because the market had simply caught up to it.

the infrastructure was fine, the list was fine, the offer was fine. the audience had been exposed to the same angle long enough that the angle itself stopped landing in replies.

THE DETECTION RULES

copy fatigue looks different from infrastructure breakdown, and you need to know which one you're actually in before you start ripping out rails.

Symptoms of copy fatigue:

• Reply rate drop is gradual, playing out over 2 to 6 weeks.
• Bounce rate stays stable under 1.5%.
• Spam complaints stay stable under 0.1%.
• Warmup scores still hold above 70%.
• Open rate is either stable or slightly down.
• All segments are affected equally by the drop.

Symptoms of infrastructure breakdown:

• Reply rate drop is sudden, happening within days.
• Bounce rate rises above 2% quickly.