To be fair, the limited amount of detail you have provided limits the amount of help that can be provided. And from what you have described XREFs are the way to go.
Not sure about "creative" work in the mechanical design field. A bolt is a bolt, and isn't going to change. Same with nuts, plate, and many objects. Those are ideal for blocks. If you have an arrangement which doesn't change much, then that is also ideal for an assembly type block - especially if its a one-off. But if you have an arrangement which *might* need the occasional re-org and you want to propagate the changes automatically everywhere its used? Yeah, XREF is the way to go.
XREFs, unlike blocks, don't necessarily need to have a fixed name. A file XREF'd into one host may be called "Fred". XREF'd into another host, the very same XREF may be called "Barney". So naming conventions won't get in the way. And XREFs can be nested under XREFs, along with other XREFs, provided a hugely flexible nesting arrangement.