One of the things doing the "One Panel" feature affords is a perspective that seems strange today when a comics company like DC has more than 50 books a month on the stands. In 1937, there were but three, and one of these was brand new though it would, in time, become National Comics' overwhelming brand. That was Detective Comics (D.C., see?), which joined New Adventure Comics and More Fun Comics on the stands that year.
And to make sure you knew to pick it up, the other books ran an inside back cover ad, which I think is pretty interesting:
Second, I love that they felt the need to confirm the image in the center of the page does not represent the comic's actual size. Turns out, Detective Comics will be the same size a More Fun and New Adventure. Was that not expected? Did a lot of people look at comics ads and think, well no, I'm not going to buy a tiny booklet for a dime? I wonder.