Once a week is definitely the sweet spot. For example, I'm subscribed to quite a few channels and I find it very difficult to keep up with the channels that post more than once a week with the limited time available to watch youtube vids. The more I fall behind, the less inclined I am to watch videos with titles that don't immediately interest me, and I might summarily unsub because of "overloading". This is why I unsubbed Jake. I would be happy to watch all his videos, one per week, but when there are 4 or 5 every week, I'd rather spend that time watching someone else.