What it does
Restricts shaking to times when at least one removable, writable volume is mounted.
How it works
Shake It On asks the file system for mounted volumes and inspects each for `volumeIsRemovable` + `volumeIsReadOnly == false`.
Where to find it
Settings → Only Shake If → External disk connected.
When to use it
Time Machine, Carbon Copy Cloner, Arq, ChronoSync — the moment you plug in your backup drive, Shake It On wakes up and stays awake until it's unplugged.