If you return to Fort Condor after each Shinra related story "paragraph" you'll be able to battle for sweet prizes. Each time though. If you absorb too much Shinra info at once, the battles will skip to the next level of prizes. Once you've reached the second disc and have already watched the (SPOILER)Weapons pouring out of the crater, you've lost your last chance to battle for anything besides the Phoenix summon and huge command.