Why do INDD files bloat over time?

[James Gifford—NitroPress]

Is there any simple reason that ID files slowly bloat over time, sometimes to absurd sizes? I know most "intelligent" doc formats keep adding app data like undo content, macros, etc., and Word is absolutely terrible at ever cleaning out or removing any of it. Cutting the content to a new file is often the only solution.

But I just had an experience with an INDD file that shocked me. Working on a long-time, episodic project (the book in the footer, actually), I started getting frustraing problems with EPUB export. Tried every fix including a wholesale cut and drop into a new doc. No go. So I did a laborious move of content to a new INDD file, which of course meant time rebuilding the TOC and some other details... but bingo. All of the quirky problems went away. Time well spent.

Then I compared the files. The new one is about 440k. The older one was a whopping 9.5M! What does ID do to keep adding junk to the basement when a document is edited and maintained over a long period of time?

[Tana Reiff]

I let the downsizing do its thing as in the preset and the new file is just fine. Thank you so much for pointing out this possibility.