I once spotted a 630 squat by myself. I have spotted 700+ as one of three spotters. I spot 500+ squats on a weekly basis. It is at the point where it is routine.
I have spotted a 510 bench press as a side spotter and 450 as back spotter.
Having a good spot is essential when you are trying something you have never done or when going all out on rep work especially squats. I have seen people puke,bleed and pass out with the bar on their back. There better be at least three people with their hands close to that bar.