Single Keyword ad group is a strategy to help you measure the performance of each keyword individually. There are several advantages of single keyword ad group and we will discuss this here.
The biggest advantage of single keyword ad group is the ability to bid the exact amount each keyword is worth. Any analysis becomes easier at the ad group level as there is only a single keyword.
More targeted ads
Separate ad group for every keyword allows you to have highly targeted ads. One ad which works best for a keyword might not work for another keyword. By creating single keyword ad groups, We allow google to select the most appropriate ad for every single keyword. Do remember that even keywords with same text but with different match type can have differently performing ads.
Device level bid adjustment
Device level bid adjustment is only available at the ad group level. So if keyword A needs to have a -50% bid adjustment and keyword B needs to have +50% bid adjustment, the only solution is to have an individual ad group for every single keyword. Otherwise, the mobile bid adjustments will be just an average value. This can negatively impact bid optimization as the correct bids cannot be executed for different keywords.
Ability to use ad group level negative keywords
In a previous article, i discussed how ad group level negative keywords help you create ad groups with zero internal competition and proper performance tracking. This strategy cannot be used in an ad group with multiple keywords as the negative keywords are only applicable at the ad group level. If you have multiple keywords in the same ad group, these keywords can compete with each other. This can increase the costs significantly.