Throughout my career at media agencies I've faced many times the question 'how many times people have to see our message to get it? We have developed tools that based on the research and common sense helped us to establish the levels of so called effective frequency. This graph from Armano's and Rubel's presentation on 6 digital trends seems to be in line what we've been doing and believing (I am curious how they've come to those numbers). Majority of people need to hear things 3-5 times before they sink in. This of course depends on the complexity of the message, the context and the environment we are communicating in. It requires crafting the messages that it are easy to understand and are relevant to people.
Though, it doesn't mean we need to push the same message 5 times through the same channel, over and over again in hope people finally get it. When message isn't relevant, they will never get it, rather get annoyed or immune over it. The repetition and effective frequency is more to me about "lightning lots of small fires" like Mark Earls says, meaning we create many contact points with people in spaces where they already are, where they are in the right receptive mode and context. It is not necessarily about sending out the same message but adapting the message to environment it is going to be seen in. Integrate and adapt, be always in beta to get best out of it and make sure people hear what you say by communicating smarter.
