Objects keep their numbers and generations, so an object that has not changed keeps its exact bytes. A numbering that cannot be written compactly is renumbered as Compact does instead: a number above 8,388,607 (the limit of ISO 32000-1 Annex C), or numbers above 1,048,576 that are more than 16 times as many as the objects, which would make the cross-reference information list millions of unused numbers.
Automatic = 0