Front Sprocket Nut

[Fazerider]

... Am I correct in thinking the nut works its way loose as opposed to a sudden catastrophic failure?

No. Earlier models have a "damper plate" attached inside the sprocket cover. when the nut comes loose it can't fall off but just rattles about on the shaft destroying whatever was left of its thread. The thread on the shaft can survive this reasonably well as its a much harder steel.
Yours probably doesn't have the plate, this gives enough clearance at the end of the shaft to allow a loose nut to fall off the end. The sprocket is then free to wander along the shaft wrecking the thread and depriving you of drive.