The guys at No Agenda call it the "6 week cycle". Every 6 weeks (not solid) to "prove" how useful and hard-working and deserving of funding they are, the FBI and various "Counter-Terrorism" units have a story of some sad sack loner who they busted for plotting to bomb something.

Almost always the entire thing is an entrapment/frame job by government agents who pick some loner, communicate with the loner for months, drive up their hate and paranoia, then offer to sell them a bomb and keep pushing until they actually agree and set up an IRL meeting to make the exchange, where they arrest him and declare "success". Since they are the ones who choose when to offer to sell the bomb or M-60 or whatever, they can time the arrest as they please.

But it's just a theory..