The following prompt appears in media check: "If you would like to test additional media, insert the next CD and press "Test". You do not have to test all CDs, althought it it recomended you do so at least once." The second sentence is confusing. That could be interpreted to mean: 1) you only have to test CD1 2) you should test all the CDs, but only 1 time (although I don't know why anybody would test them more than once.... unless they were installing multiple systems, or later going back and adding some packages they skipped the first time around.) Proposed alternative wording of the second sentence. Testing of each CD is not strictly required, however it is highly recomended. Minimally, the CDs should be tested prior to using them for the first time. After they have been successfully tested, it is not required to retest each CD prior to using again.
Used your proposed rewording, except I dropped the 'of' from "testing of each cd" so it just reads "testing each cd".