He probably did, but if you look at it, most of the early network game shows were done in New York theaters that were converted to studio space (such as the Ed Sullivan Theater, Letterman's home now, which hosted TTTT in the Moore era among others). You still see the type on TPIR with the audience below stage level in Studio 33, and the action taking place in large part in front of the "curtains" (actually, the doors).