As a frequent audiobook and podcast listener I find that most of the time long audio files of an hour or more aren't terrible to deal with until you lose your place and try to find it again while driving or running. Usually this means pulling your car over, skipping and fast-forwarding for a minute or two until you've found your place again. The free version of Audiobook Cutter lets you instead chop that monster file down into segments to make navigation easier.
The free version doesn't do much more than that, though. You can choose how long you want each segment (five or ten minutes seems to work best for me) and Audiobook Cutter will separate without re-encoding so your audio quality is not compromised. The pro version adds the capability to automatically split files in silent periods rather than time intervals and automated ID3 tag creation. I'm not sure that's worth the €25 asking price, but maybe it will be for you.
Of course you can use a free audio editor like Audacity to manually edit your files, but if you listen to a lot of podcasts or audiobooks that can get tedious very quickly.