Registering in the top 5-10 search engines of each country an organisation operates in will account for more than 95% of the potential traffic. Most existing companies will be automatically included in the search index since the search engine robots will follow links from other sites that link to them and do not require submission services.
For new companies, achieving search engine submission is straightforward. For example, in Google is an ‘add a URL’ page, but it’s more effective to get existing sites to link to a new site which the robot will follow. Unfortunately, it can take time for a site to be ranked highly in search results even if it is the index. Google allegedly places new sites in review status sometimes referred as the Google sandbox effect. However, Google search engineers deny the existence of this and explain it is a natural artifact produced by new sites having limited links, history and reputation. Either way, it is important to remember this constraint when creating startup companies or separate unlines microsites for a campaign since you may have to rely on paid search to gain SERPs visibility.
Chaffey, D. and Ellis-Chadwick, F., 2012. Digital marketing: strategy, implementation and practice (Vol. 5). Harlow: Pearson.