Animation : How many directors can direct an animated anthology series? by Tony Byrd

I would say as many as you need. One director per episode is one way.

All depends on the director and I agree with Martin ^^ comes down to their experience and how well they can run a crew. The director/ show runner for Marvel's What If is handling all the episodes himself. Which is incredibly impressive as that sounds insane lol

So. He's directing all episodes on his own.