iPod – restore and maximize battery life:
If you erase and add files in a normal manner you will get fragmentation. The iPod hard disk will have to work more to read your music and your battery will suffer.
This needs to be tested, I think: since the update process is initiated by the desktop system, it should be trivial, or even obvious, to ensure that files are written to contiguous blocks.
Apple does not recommend running disk utilities like Norton Speed Disk, Disk Scan and Disk Defragmenter. It’s not really needed as the drive is not written to and erased nearly as much as a typical hard drive. If you’re emphatic about cleaning up your drive it’s best just to do a full Restore with the Apple Software Updater. This reformats the drive (defragmenting it in the process) and has the added benefit of creating a new clean iPod database which over extended periods of use can get corrupted.
I can see how seeking and scanning could run down battery life, but I’m not convinced it’s needed.