I agree. I deciphered a few weird formats, for example the raw format of an old camera, the save files of drawings in WinWord 1. It's easier if you can make a few custom small examples, for example in the drawings use only one line, then two, then tree. They were binary formats, so the trick was to use an hex editor and look at them for a long time and make a few guess. I never deciphered them 100%, but I had enough info to read the files I care about and create new files.
Sometimes you get a riff format and a big chunk of the guesswork is solved.
And most modern formats are just a bunch of xml files inside a tar.gz , so now the first step is to change the extension to .zip and cross your fingers.
