I prefer to reference other pre-existing SOPs and forms in my protocol for executing tests, if available.
If a solution is required for testing and an SOP/WI exits for creating that solution, I would say create solution following SOP/WI XXX.
If doing cleaning verification my test protocol would say swab the tank per SOP XXX (the SOP that details how to take a swab sample) and submit to QC along with Form XXX (the QC form for submitting swab samples).
I’ve used batch records when doing media holds and often during a PQ I will list setpoints for the equipment but will write to operate the equipment following the approved related SOP (and then they will have to list which SOP they are following).
I think this makes the protocols lighter in that I don’t have to rewrite a procedure that already exits as well as make sure that the test was carried out in validation as it might in the field. My new colleagues disagree and think that this is not industry standard and that protocols must be a one-stop-shop. I was curious how others felt about this.