User blog comment:The Milkman/The Writing of the Ending/@comment-5503561-20120529204247/@comment-1388547-20120530170922

Yeah, I don't get that either. Perhaps some missions were added at the last minute, or perhaps they ran very low on space? The story is fairly linear, so I don't see why they couldn't split it across three discs if they were running into serious problems. A lot of sidequests become inaccessible after certain missions, so it would be reasonable to make the disc transitions happen at those missions.