Tracking IDs per traffic source exposed a channel paying 5x the rest

Tracking IDs per traffic source exposed a channel paying 5x the rest
The operator used one associate tag everywhere — no idea which channel earned. They split into source-specific tracking IDs (email, Pinterest, organic, YouTube). n=90 days.
— Organic: EPC $0.36 ▇▇▇▇
— Email: EPC $0.52 ▇▇▇▇▇▇
— YouTube desc: EPC $0.41 ▇▇▇▇▇
— Pinterest: EPC $0.10 ▁
Pinterest ate 30% of their posting time for 6% of commission. They reallocated that time to email and grew total earnings 24%.
So what: one tag everywhere is flying blind. Source-level tracking IDs cost nothing and reveal where your hours actually convert.