It only work if you allow it to work, it work on colonies never once work on integral part of other nation. It fail in Vietnam, S.Vietnam fall to conventional army of N.Vietnam. Afghanistan was one year assistance mission that stretch into 10 years and in foreign nation. Soviets got out, but in process 1 million less Afghans.
It fail in Bolivia, it fail in Argentina, it fail in Chile, it fail in Malasia, it fail in China, it fail in Kashmire, you give guerrila to much credit, try reading a bit more.
By way, US win with England, because France interviene and give US weapons and attack England in various areas, England over stretch.
It also fail in Tiabet, Sri Lanka, Angola, Israel, Algeria, N. Ireland. It fail more often then succeed....but for uneducated it looks like success.