The versions of "WTA" that GSN aired were "sustaining"--meaning that they did not have a sponsor and that the network is airing the show to fill time, pray that the local stations don't pre-empt for local programming that has advertising and perhaps hope that they find a sponsor. (Most likely, the only reason these kinescopes exist is that the network and/or G-T were using them to pitch the show to ad agencies--even if had been on the air for several years by that time.) The break in the middle was to accommodate station breaks, which in those days came every 15 minutes (there were still a lot of 15-minute shows back then--the first half-hour soap, "As the World Turns," wouldn't start until 1957).
In the case of the Gray "WTA," looking at a schedule back then reveals that the show *started* at 15 minutes until the hour and *ended* at 15 minutes after the hour--as a half-hour show. On certain days of the week, when its lead-in "Bride and Groom" (a daily wedding on live TV, with the lucky couple getting the gifts from the producers) ran an extra 15 minutes (no doubt because they had a sponsor for that time), "WTA" only ran for 15 minutes. Things were different back then.