Many new clients of search engine optimization companies are unsure if they should opt for one-time search engine optimization services or ongoing services. One-time SEO services are appropriate for new websites for several reasons. Once you do the initial optimization of a new website, you have to wait a while in order to receive data that will help you determine the direction in which you need to optimize the site. A period of six months or so will give you enough data to determine what will and won't work for the site.