>>1857518Playing one a week is fine i believe.
The biggest problem comes from the fact they require you to have watched all the previous streams in order to be caught up on the story.
Think how a new viewer would feel watching your stream for the first time when you are already half-way through a very story focused JRPG as an example.
They aren't going to have a clue what's going on and it could put them off watching that stream.
As i said, having one long running playthrough is probably fine but you really shouldn't have multiple going on at the same time as it requires such a dedicated amount of time from your viewers.