A major consumer packaged goods (CPG) company, one you’d recognise the name of, wanted to understand if more money could be made from one of its top products simply by tweaking its advertising and media mix. It looked at the traditional media mix it was using across display, mobile and video, the key channels used to advertise a food product. With a subtle and simple shift of its marketing mix it gained $2.5 million incremental revenues per year.

That CPG business has also decided to implement such adjustment in media investment for their next year. That might work. However, what worked today isn’t by any means guaranteed to work tomorrow.

We’re living in unprecedented times with our customers now harder to predict, segment and find them in the media ecosystem. Digital technology further empowers consumers to access any of a myriad of choices for information and entertainment, which they expect, with every passing day, to be even faster, more convenient and personalised, and above all free. That makes the customer unpredictable, and prone to snap decisions based on the weather, or the traffic, or your well thought out and well-placed advert. Or last birthday party. Or tomorrow’s vacation plans.

For all your attempts to learn and apply insights throughout the customer journey, marketing in today’s environment needs to constantly re-evaluate where consumers are, and how to drive persuasion. This requires a continuous optimization, based on direct evidence of results. Legacy understanding of the consumer behaviour becomes stale overnight, and an assurance of massive reach is a myth. This means you have to optimise your creative, your promotions, your channels and your regions through constant experiments and ‘always-on’ testing.

Recently a major telecom company wanted to understand if it could optimise advertising investment across two key products, one a traditional line and another a new product launch. The traditional line which was in market for several years, was saturating their advertising investment, and was not creating incremental sales from it. By using a software that derives saturation points by applying design of experiments, it was possible to prove that investment in the newer product line not only helped position and sell the new products, but also provided a “halo effect” in the traditional line, beyond the saturation point.

Even though the traditional product line was already saturated, the test revealed that the advertising investment in the new product line generated an additional £3m of revenue for the legacy product across a quarter.

Successes using new analytical tools come in different shapes and sizes – some marketers have driven incremental sales they didn’t think were possible, and others just find valuable savings by doing things differently – but the methodology is always the same: hypothesise, experiment, test, learn and optimise. Do it again and again. Do it continuously. Customers will feel and behave differently every day, and it is wise to learn and adjust.

So many phenomenally capable and talented marketers are deciding their strategy once, and walking away, investing faith in an activity or channel that has always worked for them before. Behaving this way in an era defined by constant change and iteration, means they are flying blind and leaving a heap of money on the table. Think how much more skilled you become as a marketer – as a business executive – by shifting investments and seeing the positive impact on sales. An impact that can be attributed to your skill alone.

Imagine the boardroom presentation you can make at the end of a quarter after you and your team identified a success was made by steering your investment in a slightly different direction in Manchester from the way it was executed in London – different patterns of channels, promotions and timings. Imagine switching from the same path your company has always followed of investing £2m in TV, because an old study thought it was enough, to an investment of £10 million that drives fantastic scale in sales. Visualise too what it would feel like to fund such TV investment with money saved from cutting investment in an old keyword search list strategy that was short in results.

We in marketing need to stop flying blind. We must use evidence to support our investment cases, allowing to further scale our company ambitions. Those already doing so are finding that they are being listened to in a way they never have been before.

Sandro Catanzaro is the co-founder of DataXu.