Best Answer Memnoch73 , 09 October 2013 - 01:54 PM
This is leftover from the change of when the bootloader was first unlocked. At first the Safestrap roms needed to have you mount system to install. This was due to the way SS worked. If you are flashing something current there should be no need to mount system and I have never seen a need to mount everything. If by chance you try and install something and get a bootloop you can troubleshoot by trying a mount system install...
There is a bunch of other details that others can probably explain better but that's the gist...
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