In my opinion you can ditch drawings 0-A2-15 - A2-29.dwg and 0-A2-30 - A2-42.dwg.
On each tab in the original drawing 0-A2X-sheets.dwg there's a block instance in the bottom right hand corner. It's either one of two blocks, let's say block 'A' and block 'B'. Neither are tiny definitions.
Converting both blocks to xrefs, say drawings 'A.dwg' and 'B.dwg' respectively, and then converting said block definitions to xreferences, remapping the block references to same, purging thusly, reduces the file size of 0-A2X-sheets.dwg from 7,390 KB down to 650 KB. Not a typo.
Sorry to sound vague. I don't wish to betray Will's confidence. I figure the above illuminates the problem without revealing anything proprietary / confidential.
- Michael.