Cam break-in on flat tappet systems is not a mysterious process. Use the right assembly lube, fire the engine and don't let it idle but instead run it up to 2500 RPMs and vary the RPMs for the first 15 minutes, and if you're anal (or the flat-tappet engine is in an aircraft), cut open and inspect the oil filter media at the oil change.
Implying that a poorly made or improperly broken in camshaft is failing in 300 miles because of new oil additive packages makes me question why the Economist is publishing poor articles on fringe motoring topics. Improper assembly, pre-lube or engine start of fresh rebuilds has been wiping cam lobes for 6+ decades now.
PS: For infrequently used engines with flat tappet, splash-oiled cams, use CamGuard: http://www.aslcamguard.com/ It's not cheap ($26 a pint or so), but it's well regarded in the piston aircraft world (where light airplanes frequently sit for weeks at a time, unlike your daily driver, but very much like your occassional usage of a 60s Mustang).