It works up to a certain level. When you start, unless you have a following on another social platform, you start from zero. The algo ain't going to send you traffic. You won't get any "real" viewers, and by real, I mean people without channels. All your views come from other channels. Everyone is in the same situation. The only way to get views and subs consistently day by day is to engage with other startup channels in your vertical, scratch each other's back so to speak. That's why everyone does it, b/c there's no other way. So it works, but up to a certain point. Certainly for your first 1k subs, perhaps into the 2k range. Once you are in the 1k-2k sub range, your new vids should get 200-500 views out the gate, which in many cases is more than the 100 sub channels that get 10-20 views. So your vids start getting into suggested spots on other 1k-5k channels, and it builds slowly, very slowly, from there. Once you start getting real traffic from real viewers, the sub strategy is pointless as you real traffic far eclipses the sub channel traffic. That's why you don't generally see 5k+ sub channels engaging in it. There are caveats to this strategy, and you need to make yourself aware of them prior to implementing it.