I would hope that perhaps something like Kids Click could be made into a full time subchannel. But then how many stations would carry it?
As has been mentioned in several previous posts, kids and teens can find what they want on cable and on the internet 24/7. A kids subchannel only makes sense for people who can afford neither cable nor internet and have only OTA TV. Those families' kids can watch E/I programming or PBS children's shows when they're on, and maybe sleep, read, play music or go outside and get some exercise when they're not. Another children's network on a subchannel is a cure for which there, largely, is no disease. On the other hand, Grit, ME, and similar subchannels showing old movies and old TV shows have plenty of potential viewers -- mainly retirees on fixed incomes who don't see the need to pay for cable or subscribe to a streaming service (if they have internet).