There is a certain number of test monitors under each rate plan: 2, 5, and 20, respectively. Each test monitor can only be customized for one type of inspection. You can monitor several websites under one rate plan by customizing the test monitor for a particular type of inspection for each website. E.g.: the Advanced rate plan allows you to monitor one website according to all three available types of inspection and customize the availability check for another one/two website(s).