This topic has been a matter of debate for long now. I often get this question from people if they should outsource all his marketing and promotion needs to one company only, or to more than one agency.
The logic behind this practice is that different agencies can use different strategies and insights to improve performances. It’s not the reality. When you hire different agencies to work on different marketing channels, not even single one can be effective. The reason is obvious, one channel of online marketing compliment other. For instance, PPC and SEO together works. An agency that works on search engine optimization can optimize pay per click advertising campaigns as well very well. The data from one channel proves helpful in other channel. For instance, if you know that certain keywords are bringing relevant traffic to the website, but it’s not increasing overall conversions, you can have dedicated brand specific campaign with paid ads and can have customized messaging to appeal more to the end users.
Organic listing does not allow you to change the texts that show up immediately, it takes a lot of time. But a paid campaign with PPC services can have custom ads with customized messaging almost immediately.
Not just that, if the same online marketing company is running both your organic and social media marketing campaigns, it can very well optimize social media campaigns to get more social signals from different websites and thus can help in getting organic ranking as well. As an agency running SEO campaigns would know that social signal is one of the ranking factors and hence would work accordingly. If the different agencies are working on it all differently, the overall impact on the website traffic will not be very rewarding.