The format you're using simply doesn't work in the long run. I've seen a ton of channels do what you do and say they're doing it to give back to the community. But in reality, you're trying to artificially drive traffic to your channel by requiring them to be active. So while they're active, you're using each other and you're OK with it. They're obviously didn't sub to your channel and watch your videos because they want to view their stuff-they're only doing it because they get something in return-once they have that, there's no incentive to stay active. If you end up doing the shout out videos too often, they become meaningless to your audience-which doesn't benefit your channel or the channel you are shouting out. Shout outs shouldn't be used to solicit views/subs. If you truly like another channel or someone has done a favor for you, then use a shout out as a reward and expect nothing in return. You will be surprised at the good mojo that comes your way when you use a shout out the properly.