Well said null.
There have been several audit and inspection findings where the investigator has not been present in the clinic, on the date of the signature on a document signed in that clinic! Calling into doubt the veracity of the whole process.
From a legal point of view I would not sign a blank cheque or blank contract, and then let others complete the information for me, so why would investigators do this?
I find investigators and their staff endlessly inventive. I have seen all sorts of ideas as to what the “date” data-field means. It’s quite simple – the signature date, is the date of signature! Difficult to see how that could be misunderstood? The date of signature must be attributable and contemporaneous. With more requirements for both date and time of signature (e.g. date & time of both “prior interviews” and the consent interview, [where necessary to show “ample” time]) it is even more important that these dates and times are under the direct personal control of the signatory. Personally dating a signature helps ensure that it is less likely that there is falsification of dates by others (e.g. pre/back dating). It makes sure that the “audit trail” is genuine and has integrity. Having others date a signature (or pre/post-date) violates the requirements of Data Integrity guidelines ALCOACCEA (FDA; EMA; MHRA; WHO). Violating this process puts into doubt the veracity of all data and information from that investigator site!
I have seen cases where the PI has signed in advance many consent forms, and leaves others to complete the rest of the details. Making a mockery of the investigator signing to attest that freely given informed consent was gained according to GCP guidelines and applicable laws. If personal dating is in effect, then the date (& time) that the PI signed would be clear and can be matched with the date (& time) that the subject signed. Genuine informed consent is the cornerstone of GCP and failing to comply with GCP is a very serous violation.

Part of your CAPA must be that the investigators and their staff are fully trained on GCP and have understood that training!! Clearly, at the moment, they don’t seem to understand how to operate in a GCP environment.