Think of seasonal marketing like airline pricing. Flying on December 23rd costs way more than flying on a random Tuesday in February, but the plane gets you to the same destination.
You spend $10,000 on Facebook ads in July and generate $20,000 in revenue. Not bad—2x ROAS. Then you spend the same $10,000 in December and generate $30,000 in revenue, but you only got half the impressions.
This is the seasonal efficiency rollercoaster that most marketers pretend doesn’t exist.
The budget planning lie we all tell ourselves
January budget planning season arrives. You pull last year’s numbers, calculate averages, and spread your budget evenly across 12 months like peanut butter on toast.
“We’ll spend $50K per month on paid social. Consistency is key.”
Fast forward to March, and your campaigns are barely breaking even. July hits and you’re wondering if you’ve forgotten how to do marketing. Then November arrives and suddenly every campaign is a winner.
Here’s what nobody wants to admit: your marketing dollar isn’t worth the same amount year-round.
The fourth law of marketing
Marketing is inherently seasonal, and marketing efficiency changes depending on the season. Your dollar may go further during Black Friday, but impressions are more expensive. Likewise, during your down season(s), your dollar may not go as far, but impressions might be cheaper.
The same ad, same audience, same budget can deliver wildly different results depending on when you run it. And the relationship between cost and performance isn’t what you think.
The December paradox: Higher returns, higher costs
During peak season—Black Friday, Christmas, back-to-school—everyone’s fighting for the same audiences. CPMs skyrocket. But here’s the thing: people are also way more ready to buy.
We see this with our clients every year. A beauty brand might pay $15 CPMs in December versus $6 CPMs in March. But their conversion rate in December is 3x higher. Their average order value jumps 40%. Their customer lifetime value increases because holiday shoppers tend to be higher-value customers.
So yes, you’re paying more per impression. But each impression is worth more too.
The July drought: Cheap impressions, expensive conversions
Now flip the script. July arrives and CPMs are dirt cheap. You’re getting impressions for half the price. Your reach metrics look amazing.
Then you check your conversion data and reality hits.
Those cheap impressions aren’t converting like they do in November. People are on vacation, saving money, focused on summer activities instead of shopping. Your cost per conversion might actually be higher in July despite lower CPMs.
This is where most marketers make expensive mistakes. They see cheap inventory and increase spend, thinking they’re getting a deal. But cheap impressions that don’t convert aren’t a bargain—they’re just cheap.
The seasonality trap that’s killing your ROAS
Here’s the pattern we see constantly: brands judge their campaigns by the same ROAS standards year-round.
“We need 4x ROAS minimum.”
So they scale aggressively when they hit 4x (usually in slow seasons when conversions are harder). And they panic when they drop below 4x (usually in peak seasons when they should be scaling).
A 3x ROAS in December might be incredibly profitable because you’re capturing high-value customers at scale. A 5x ROAS in July might be less valuable because you’re getting fewer customers with lower lifetime value.
Your efficiency targets should move with the seasons, not stay static year-round.
This strategic gap is costing you millions
While you’re spreading your budget evenly across the calendar like it’s a democracy, your competitors who understand seasonality are concentrating firepower when it matters most.
They’re reducing spend during low-efficiency periods and going all-in during high-conversion seasons. They’re adjusting their ROAS targets based on customer value, not arbitrary standards.
Some brands walk into Q4 with budget strategies that account for higher costs but target higher returns. They spend less when efficiency is low and more when efficiency is high. The result? They capture disproportionate market share during peak seasons while their competitors burn budget fighting seasonal headwinds.
The cruel irony? Most brands have this seasonal data sitting in their analytics right now. They just don’t know how to use it strategically.
The seasonal strategy you’re missing
This is why our MMM tracks efficiency patterns across different time periods, not just overall averages. We can show you exactly when your marketing dollar works hardest and when you’re fighting an uphill battle.
Because here’s the truth: seasonal marketing isn’t about spending more in good months and less in bad months. It’s about understanding when to optimize for scale versus efficiency, when to acquire customers versus retain them, and when to build awareness versus capture demand.
Understanding Law #4—that some parts of the year, each of your marketing dollars goes further—helps you work with seasonality instead of against it, but there’s an even bigger timing issue most marketers completely miss. Because marketing effects don’t just vary by season—they unfold over time in ways that make isolated testing almost useless.
Next week, we’ll explore Law #5 and why that incrementality test you ran last month probably told you nothing useful about long-term performance.
Cody Greco is the co-founder and CTO of Prescient AI. He conducts the independent research that makes up the foundation of Prescient AI’s proprietary MMM, building our model from scratch based on marketing dynamics in the real world and reporting marketers need to know to optimize their paid media spend. He blogs about MMMs on his own website and guest lectures at universities when he isn’t coding a new feature. Before Prescient, he established and scaled Grubhub’s research science team and went on to lead their global machine learning organization. Cody holds a B.S. in Operations Research from UCSD and M.S. in Computer Science from Georgia Tech.
