I'm guessing that "guessing in the dark" is the way experiments for particles in the standard model have been done for a while now. I would assume that a single success would set off a chain reaction as the author said.
I'd say it's not completely in the dark. The experiments try to test theories that suggest where to look. For instance if a theory predicts a previously un-discovered particle, with some rules for how it interacts, then you can refine your search based on those rules -- what range of masses you're looking for, what decay patterns, and so forth.