Automator Action - Copying to 7xUSB

[JeffCGD]

I am trying to construct an automator action to efficiently copy a 15Mb folder containing 9 items to 7 512Mb USB memory sticks connected to a powered 7-port USB2 hub. I have 950 of these memory sticks to do this to (yes, it's for work).

Copying the files to a single USB memory stick takes about 20 seconds. Copying the files with an automator action is taking more than 10 minutes!
This is with an action that does:

Get Specified Finder Items (the 15Mb folder of files) --> Copy Finder Items (to GENERIC usb volume 1) --> Copy Finder Items (to GENERIC usb volume 2) --> Copy Finder Items (to GENERIC usb volume 3) --> Copy Finder Items (to GENERIC usb volume 4) --> Copy Finder Items (to GENERIC usb volume 5) --> Copy Finder Items (to GENERIC usb volume 6) --> Copy Finder Items (to GENERIC usb volume 7).
This took about 10 minutes.

I even tried putting the Get Specified Finder Items before each Copy Finder Items. This took 24 minutes!

Can anyone tell me what I'm doing wrong, and what I can do do do it correctly?
Thanks in advance.