“Diversifying for the sake of diversifying is often times a bad idea. A new channel's ROAS doesn't just have to meet the ROAS of the other channels that could have absorbed that budget — it has to exceed it, because you're supporting a new channel.”

Diversifying UA channels for its own sake destroys performance — use the waterfall method instead

Seufert's waterfall model: max out the biggest channel until it hits your ROAS threshold, then move to channel two, then three. Adding a second channel before saturating the first adds overhead without proportional return. Diversify only when you've hit true saturation or when a brand-oriented channel lifts blended performance across the portfolio.