Weren't a lot of the third-season scripts left over from season 2, though? I thought I read somewhere that they didn't really have the time or opportunity to develop many stories of their own, so they had to draw on what was already in inventory.
It's less material leftover from season two, and more material bought for season three before Freiberger was brought on board
Star Trek. He was hired for the series on March 28, 1968 and reported for work on April 1, 1968. At that point, the following episodes had stories or scripts that were already in work:
"The Way to Eden" (at that point, "Joanna")
"That Which Survives (at that point, "Survival"
"The Enterprise Incident" (at that point, "Ears")
"Elaan of Troyius" (at that point, "Helen of Troyius"
“And The Children Shall Lead"
“Spock’s Brain”
“Wink Of An Eye”
"Spectre of the Gun" (at that point, “The Last Gunfight”)
"Let That Be Your Last Battlefield" (at that point, “Down From Heaven”)
"The Paradise Syndrome" (at that point, “The Paleface”)
“Day of the Dove”
So, that's 11 out of 24 produced episodes. Add to that the two episodes that Gene Roddenberry furnished the story for ("Turnabout Intruder" and "The Savage Curtain") and you have 13 out of 24 stories that were brought in without Freiberger's involvement. That's not quite as high as the number of episodes Freiberger claimed were brought in without his involvement in
Starlog 39 (
http://www.billcotter.com/projects/starlog-39.pdf), but it's more than half of the episodes produced in season three.