% is a bad threadshold for many nowadays applications, unfortunatly most developers seems not to think about what it means in reallife.
Why?: read ahead
[Media Library] Your disk volume has less than 5% free space on /share/MD0_DATA/. Related functions will be stopped unless you free up additional space. Please free up more space for the Media Library to continue running.
great in a world with 3TB+ HDDs where 5% is more worth than 150 GB!!! There was a time 150 GB HDDs didn't exist and we had Windows, 10 Games, Word and ALL our Music stored on the disc ... c'mon.
Microsoft Battery Management in Windows
Another pre-defined 7-5% Level (thank god, in newer Windows versions you are allowed to lower them manually, this wasn't possible in past days).
These levels are fix, never mind how good your battery is. For a 8h battery, 10% lower level equals around 45min time left. 7% equals 30min and 5% still more than 24min. Still enough time to work ahead, safe your documents and shut down. Windows doesn't ask the user if he want to shut down later or it should hibernate automatically. Still, I'm aware of the new Win8 auto-update feature and "it should give a user best experience" if it suspends / hibernates automatically and you can still resume if a power adapter is attached. Unfortunatly, up to Windows 7 (I didn't tested it on Win8 yet) windows doesn't recognize really critical power level in suspend / hibernate mode, so your work will be lost if it automatically suspends but you forget to attach a power adapter within the next hours.