I've found that when I put my buggy on my buddies Hudy setup, once I put the wheels back on the car the camber looks off. I set it for -2 on the Hudy, put the wheels on and measure it with a RPM camber gauge it measures 0
and yes I always set it at ride height before anyone asks
I would say if you were a serious on-road racer, it's a must. Offroad, not as crucial.