Projects have the perfect functionality for collaboration, if you want to share specific objects.
However shared documents (objects of type wtDocument) cannot be updated with the "Update Project", "Update Selected Shares" and also not with a scheduled synchronization. If a document has a new revision in PDM, the project will not get any notification or ability to update it.
There are cases, where projects are used to share specific structures (e.g. for manufacturing in other locations) and with the current behavior it is impossible to keep the documents up to date. The result is, that the target location produces parts with old and wrong drawings.
A workaround with identifying the documents in a report is time intensive and not acceptable for the user, that is responsible for the project.