There are many schools of thought around this topic and quite frankly, most of them are correct. There are Pros and Cons to both situations.
Let’s take a look at the In-House SEO first.
They get a deep sense of the company brand and how they want to portray themselves online. Typically, the in-house gets full access to all data and is involved with all marketing decisions that are tied to SEO.
They can help provide insight as to why certain things happen on the site, and provide strategy on next steps.
The SEO consultant can provide all of the above and more. While the In-House focuses on one brand, the seo consultant is exposed to many industries and helps to solve the various challenges they are met with.
SEO Consultants need to stay on top of current trends. They have a network that is probably much broader than the In-House SEO, which means they can contact other experts who can fix any issues that might be at hand.
The consultant is a monthly expense. If they don’t provide value, you can part ways and cut your losses. With an employee, there is HR and unemployment issues to potentially deal with.
The In-House seo might get too comfortable in the role and let things slide. The SEO Consultant needs to stay on their toes and constantly prove their value every month, and every time they talk with you.
The choice is yours. Where it makes sense on some levels to have the In-House SEO as the answer to your problems, in most cases, keeping the consultant also means having access to the latest techniques and strategies for success.