The answer is BOTH.
An SEO professional must constantly update his technical knowledge and improve his skills.
Only experience, creativity and constant testing can lead an SEO expert to the right combination of proven techniques that will achieve the best results for his clients.
SEO periodic table of factors (summarised)
The Periodic Table of SEO Ranking Factorsis a handy reference that shows the most important factors in achieving good search engine rankings, presented in the familiar layout of the periodic table. Also included in the graphic is a brief explanation of each element and why it is important. Elements are assigned point values, too, to give you a sense of how important they are in the overall scheme of things.