When should I use a Two Click Implementation instead of a One Click Implementation?
Fabulous recommends testing your domain names first using the One Click Implementation (the default setting). Two Click Implementations should be considered for those domain names which are ambiguous, domains considered to have multiple connotations or those identified in the “Underperforming Domains” report.
For example a domain containing the phrase "really fast" could potentially relate to motor sports, internet connections, fast food, transportation and many other subjects. In such a case it is generally best to use a Two Click Implementation and let each visitor decide which results they are interested in.