I don’t recall the exact situations where new USB devices aren’t recognized, I’ve just had mixed results with getting new devices seen and wanted to pass on a tip to avoid having to reboot if there is a problem. It’s also handy if you’re using a USB-SD card adapter and want to swap the SD card for another one, since the Domino doesn’t seem to pick up on the presence of a different card without unplugging the USB-SD card adapter or performing a USB reset.