To me what Lucas says makes more sense, because all Kurtz says is he doesn't understand why they wouldn't have tried more takes if that was really what Lucas wanted. It's also important to note that the reason Lucas and him had a falling out was because in Lucas' words "he wouldn't say no to anything." They went their separate ways becuase the budget blew out of control on Kurtz's watch.
So it doesn't suprise me when I hear Lucas saying he cut his losses after 3 takes, and for Kurtz to wonder why he didn't just keep trying until he got the shot he wanted.
To me Kurtz's account only bolsters Lucas' claim.