According to Google’s documentation: “Seasonality adjustments are an advanced tool that can be used to inform Smart Bidding of expected changes in conversion rates for future events like promotions or sales”
On paper, this sounds like a great solution to test when youβre struggling to increase spend (as was my case).
But in practice?
Using seasonality adjustments essentially tells the algorithm: “Hey Google, my conversion rate is gonna be higher so send me the WORST quality users ever because my creatives will convert them anyway!”
As mentioned above, we wanted to scale the spend during Christmas and hereβs what happened when we aggressively adjusted conversion rates (claiming our Christmas creatives would convert 100% better):
β We could scale (+41% spend) βBut CPA was the worst of the year (+62% compared to the previous period) βThe worst CPI of the Q4 (+64% compared to previous period) β ROAS and LTV dropped by 30%.
The takeaway? If you want to test this feature, do NOT use it as a way to scale your spend because you’re basically opening the door of your house to the worst guests ever!