With issue #41, Stan and Jack began a series of longer, multiple issue arcs. This one, the first of three-in-a-row, featured The Frightful Four. Frankly, there’d been quite a bit of this villain team in recent issues, so it wasn’t all that exciting–but it was interesting to see a similar story play out over three issues instead of one. Stan and Jack seemed to be experimenting with less compressed storytelling.
Fantastic Four was selling extremely well, so they probably figured they had a loyal fanbase and could be assured future sales so they were free to expand the art form a bit.
Creators: Stan and Jack