With my load out of Tarkin, Yularen, and Enhanced Armament, if I ever get to yaw just a bit, I can get a shot off from the side hull, use a concentrate fire token for a re-roll, exhaust Yularen to gain it back, and then fire from the rear hull zone and use the token again for another re-roll. Then on my next Ship Phase I'll gain the token back from Tarkin. The CR90s only have 2 shields up front, so if you pound it, you'll eventually get them to back off or blow up.
While you can get the token back using Yularen you can not use that command again for that ship in the round. You can only issue the same command once. You can spend the CF token, get and back, but not use it again because the CF command was already issued when spending the token. Or, one can use the CF dial and spend a CF token at the same time.
I was schooled on this in the rules subforums. First paragraph under Commands describes that a command is the dial or a token. The first bullet point on page 4 under the command token descriptions says that the same command can only be used once per round. The second bullet point allows the command on the dial to be used with an existing command token.

