Clarification on running roms from usb drive please

[chubsta]

I have read the docs and am sure I understand them, but just want to make sure...

I want to store all my roms etc on an external USB thumb drive.

I have read the docs and it all looks simple enough if I use
Automatic Mount (Easiest Method)

**As of December 30, 2016 a simple automated method was added to run roms from a USB drive.

Create a folder called retropie-mount on the USB drive
Plug into Raspberry Pi
It will proceed to automatically copy the RetroPie folder AND all of its contents (you may need to reboot to start the copying)
NOTE if you have a large ROM collection already on the SD card it will copy all of the ROMs too so make sure your USB is large enough. It is easiest if you haven't added any roms yet.

Once the folder structure is copied over the USB will be mounted over the RetroPie folder so any ROMs you add to your pi will be run off of the USB.**

What I am unsure about is whether I have to then do the instructions listed under:
Transfer the existing RetroPie file structure

From reading it it would make sense for me to do it but just want to make sure before I mess anything up.

I know, I should be bright enough to work it out but it is not obvious where the instructions for 'Manual Mount' end (but then I am not the brightest...)

[mitu]

@chubsta said in Clarification on running roms from usb drive please:

Transfer the existing RetroPie file structure

That's clearly under the Manual Mount section and - obviously - in direct contradiction with the previous sentence from the Automatic method

It will proceed to automatically copy the RetroPie folder AND all of its contents (you may need to reboot to start the copying)