The phillipines insurgency was a shit show and the only success America had with it was in pretending it never happened and killing enough Flips for them to know it happened but not all the details.The US military does a terrible job of following those rules. It understands the concepts of counterinsurgency at a high level, but it really isn't geared towards fighting unconventional opponents. Countering a foreign insurgency with conventional forces is fucking hard, and I don't think we've really pulled it of since the Philippines (and I don't know much about that). Democratic nations would do well to steer clear of insurgencies in general.
Suffice to say it was what would happen if the Mongols thought they had a higher purpose then looting and stealing combined with every war South Africa fought ever prior to Mandela. You got child soldier hopped up on cocaine rushing US machine guns, the odd village massacred in retaliation, entire Army Units going full Apocalypse Now and at the end everyone agreed this whole thing isnt working out so we need to get going now.
And yet somehow after all of that we were still better then the Japs. Really makes you think.