COSAC

When Google growth hits the ceiling

By 2025, COSAC’s digital advertising strategy was approaching its limits. With strong visibility and sales already driven through Google Ads, the challenge was how to keep growing without burning efficiency. Rising CPCs, tougher competition, and SERP changes were pushing Google to a saturation point. Simply spending more would drive diminishing returns.

COSAC, a leading provider of online training courses, needed to reach new customers without overspending in a market where price competition was already fierce. The risk was clear: relying too heavily on Google would cap growth and limit long-term scalability.

Building a Microsoft-specific strategy, not a replica

Door4 analysed Google Ads performance to identify spend breakpoints where efficiency dropped off. Forecasting models projected that adding Microsoft Ads could deliver around a 10% uplift in overall paid revenue, with less competitive CPCs and a complementary audience profile (older demographics, workplace devices, and Bing defaults).

Rather than replicate Google campaigns, Door4 designed a Microsoft-specific strategy. SafetoSite Green Card campaigns were prioritised, with fresh keyword sets, custom ad copy, and tailored negative lists to capture intent efficiently.

The goal was simple but ambitious: restore growth headroom by delivering incremental volume at a stronger ROAS than Google, while reallocating inefficient Google spend into Microsoft to protect overall efficiency.

Phased testing, hands-on optimisation, incremental gains

The Microsoft Ads programme launched in June 2025. Campaigns were closely managed, with manual bid adjustments and week-by-week optimisation. Reallocation of budget was carefully controlled so growth came from incremental activity, not just spend shifts.

Door4 took a phased testing approach, first proving the viability of Microsoft Ads with specific campaigns before extending the model across other course areas. A balance was struck between rapid scaling and ensuring early performance data was clean enough to inform bidding and keyword expansion.

This hands-on management allowed the team to quickly refine campaigns around the behaviours of Microsoft’s audience, which did not always mirror Google’s. Insights from ad copy testing, keyword intent, and device performance were fed back into campaign optimisation, strengthening efficiency with each cycle. By treating Microsoft Ads as a distinct channel, COSAC avoided duplication and gained a genuinely incremental stream of leads.

Stronger ROAS, higher volume, sustainable growth

The Microsoft Ads expansion delivered significant improvements in lead volume, efficiency, and overall paid media performance, creating a more sustainable, multi-channel acquisition strategy.
Within the first three months, the Microsoft Ads campaigns exceeded forecasts:

• ROAS consistently outpaced Google, averaging 2.68–4.65 compared to Google’s 1.7–1.95.
• Overall, COSAC achieved a 20% uplift in total paid revenue, double the original forecast.

The immediate impact was not just more leads, but more efficient leads, relieving Google of pressure while opening new, sustainable growth channels.

Diversification, resilience, and a scalable growth path

The project proved the value of disciplined diversification. By modelling realistic outcomes, reallocating inefficient budgets, and tailoring Microsoft Ads to COSAC’s needs, Door4 helped unlock new growth while protecting ROAS.

Equally important, it showed COSAC that performance marketing can scale beyond Google if approached with rigour. The structured rollout created a repeatable framework for testing and validating new platforms, reducing reliance on any one channel. In a market where platform costs and algorithms shift constantly, this flexibility is commercially vital.

Beyond solving an immediate volume challenge, the Microsoft Ads success gave COSAC confidence to push further. With the foundations laid, the business is now positioned to diversify into paid social and other performance channels, building resilience and securing a scalable path to long-term growth.