PQ isolator sterility testing

Hi all,
I am trying to write up an isolator’s PQ for sterility testing. There is already a very interesting “protocol” authored by Ankur but I am wondering how flexible we can be regarding the 11 checks that he is mentioning. For instances, the integrity for HEPA filters is done during the IQ, OQ and service. Is it really necessary to do it during the PQ? I will assume that the PQ will be something “similar” to the OQ but I do not want to miss any checks or incur in extra checks. Any advice/suggestions/recommendation are always welcome,