With your wheels centered and servo on, if you forcefully pivot the front wheels, the servo saver should give before the servo strips out. If it's adjustable, you usually start with little tension on the spring, then adjust accordingly so that the servo saver separates/compresses the spring before the servo gives. It also absorbs the shock vs the wheel or tie-rods absorbing it.
It's like a slipper clutch. It's there to absorb the shock of an impact. 1/8th scale buggies are typically the toughest RC available. Arms are short and fat, hinge pins are large, wheels are smaller and string, little sidewall on the tires and a wing to hit the ground before the engine on topside landings. Everything about them is just tough. The spring loaded servo saver is just one more thing making them durable.