Interesting.
I've never had an asymmetric flap failure (a couple of symmetric ones in a C150 and an AA5), but whenever I've run the certification programme on a single which had flaps, I've always insisted on a run through the design of the flap circuit and if there seems any reasonably high probability of an asymmetric flap failure have insisted that we test the aeroplane with asymmetric flaps to ensure adequate controllability.
The way we normally did it was to disconnect flaps on one side, get airborne and climb to a safe height flapless, then progressively select flaps - so we'd only get it on one side - then simulate typical manoeuvres including an approach and go-around.
I don't know if Piper and Cessna, for example, do the same thing?
G