How do hydraulic flat tappet lifters fail?

What I do is oil the lifters and install the valve train. Prelube to get oil pressure and turn the motor over by hand. Then I watch each lifter as I spin the motor by hand. If they don’t spin, I pull it apart and look at that lifter/lifter bore/cam lobe to try and determine why. A nick or burr, a bad lifter bore, etc. For me they must all spin when cranking by hand, if not, I don’t run it.