Q: Each time I connect my new fifth-generation iPod to iTunes, it always updates a number of songs (whether just a few or 50+). I certainly don’t recall changing any settings or properties in iTunes about the song between syncs. Is this a common issue?
A: If there’s one thing we’ve learned about iTunes’ iPod syncing over the past few years, it’s “trust it.” iTunes’ synchronization engine has proven incredibly reliable, and there’s almost always some reasoning behind what it does.
Tagging, adding album art, and several other song-specific operations in iTunes will trigger the need for that song to be replaced on the iPod. However, since you’ve indicated that you don’t think this is the problem, we’d bet that you’re using “Automatically update selected playlists only” mode, where at least one of the playlists you’ve selected are Smart Playlists based upon, for example, playcount, which will change the makeup of the playlists between syncs.
Alternatively, the files synchronizing could be Podcasts that have been downloaded between syncs without your knowledge.
That said, no software is infallible. If you truly feel that the synchronizations are unwarranted, you can always attempt changing synchronization methods or restoring your iPod.