I often (not always) have models where there are a relative few different fairly simple parts, but there are a lot of them used. That tends to be a different issue from a case where there are a lot of different and potentially complex parts, each used once or perhaps just a few times in the project. The practical requirements for drawings and the drawing structure are very different in those two scenarios. One can be handled manually, the other is better not handled that way. Both needs would be served by a "project directory", and many needs related to that would be vastly helped if a "parts library" function was available. However, a "parts library" comes with drawings associated with each library part. I do not know how pre-existing drawings would integrate into a "one-piece all encompassing" drawing structure. They work fine with the "assemble your own" type structure, so long as the drawing of the part can be on a separate sheet. It's more difficult with multiples per sheet, since there is some problem of "linkage". The "Alibre model" of workflow assumes a drawing will be created for each part in the model, at the time of model creation. Linking a pre-existing drawing from outside into a drawing appears difficult, but a pre-existing linkage to a separate sheet part drawing seems to be OK. I think the ability to have some sort of functioning part library, and the ability to have a "project directory", neither of which exist now, is something that needs to be a priority.