I go through phases, and I think it is me rather than the wishbones - but I can go for months and months and not break one. Then go through loads at one event, such as Stotfold national last year, think I did 5 between 2 cars.
I consider them to have a sweet spot - where if caught at a particular angle they'll go with little force, whereas othertimes I can cartwheel for miles, or nose dive from a jump and it keep on going - unweakened.
Also same with towers, can have some large crashs and it'll be fine, then on a relatively lame roll the familiar crack noise brings a broken shock tower.
Perhaps it is the phantom noise that breaks the plastic rather than the crash.
