The important thing to know about network effects is that once you have one going, it's much easier to build all the other defensibilities on top of it, including other network effects. This "reinforcement effect" is often underappreciated by Founders, especially when they're preoccupied by growth. Continually looking for and launching new defensibilities is important because they reinforce each other: the more you have going the better they each work up (although this is only up until a certain point, because trying to do too much at once can detract from operational focus).