Tomorrow night you can catch Jimmy Kimmel’s first show at his new time slot. ABC moved Kimmel’s show up half an hour to compete directly with Jay Leno and David Letterman, who start at 11:35 p.m. Or at least, Leno used to start at 11:35. After Kimmel announced his move, Leno also decided to move to a new time. His show will now start at 11:34. At stake is about a half a billion dollars in ad revenue. But will a one-minute head start really make a difference in the ratings?

Jon Swallen doesn’t think so. He’s a chief research officer at Kantar Media and he says people have largely made up their mind about which TV talk show host they prefer. “A one minute difference in start time isn’t going change that preference.”

And if one minute really did make a difference, why do the networks give up five of them by starting their shows at 11:35 instead of 11:30? Swallen says “it’s a concession to the local affiliate stations.”

The networks give those minutes to their affiliates so they can squeeze a little extra ad revenue out of their local news. But it’s not completely altruistic. Late night shows rely on local news to draw an audience that will stick around for them.

“They want to go seamless from the local broadcast into the late night show,” says Ann Easton, a contributor to Yahoo! Television. Even though she knows the inner workings of seamless programming, she still can’t resist it. “I’ll be honest, I watch the local news and that’s exactly what happens to me a lot of times. I’m like, hey, look who is going to be on Letterman tonight or Leno.”

But networks now have way more competition then they used to. With dozens of cable channels to compete for ad revenue, that one minute of network programming isn’t as valuable as it used to be.