"It'll only take a minute" saying

My father, who died a few months ago, was a ww2 vet. He would sometimes say “it’ll only take a minute” in a slow deliberate manner if he was asked to do something. I asked him where that came from and he shrugged and said “I don’t know, we used to say it in the big two”. In the movie green berets with John Wayne, a pilot of a plane radios back to John Wayne and says it in that exact same monotone way. Then, there is a 1940s war movie where a soldier grabs an intercom device on the back of a tank and asks the tankers to blow up a bunker. The response from the gunner is that same “it’ll only take a minute”. anyone know the origin of this or heard other vets from that war say it? my guess is a radio show from the 30s, but I can’t find reference to it anywhere. Thanks.