What Randy said :kewl:
I am currently working with a drawing that has the work as xref, the border, and both of those xref-ed into another file with only a block containing the border data, and the two xrefs, that is three dwg files for one drawing :ugly: and as long as there is a block with attributes... why not include the border linework as well? As the other xref is compleat except for a paperspace border, how is it necessary for that to be an xref as well.
As Randy pointed out any of those xrefs might be accidentally over-ridden or changed, and not have been saved at the time of publishing. I have seen many total republishing of 50 drawing sets, it is quite easy to use FIND or a lisp routine to change all the sheets in a single or very few moves.
I have several block update routines (depending on the situation) that make blocks no different than xrefs except, they only change when you tell them to, they are always in the drawing, and they have attributes