I used to event on my pony, Wildey. He was a funny one - I had to be there supporting him 110% to every showjump (Stadium fence? We don't call it stadium in Australia) or he would stop. Drop a hand, relax your core, he would stop. No matter how well set up, how perfect the striding, if you weren't there with him he just wouldn't.
Get him out on CC? You could throw the reins away and bounce along like a noob and he would get you through the toughest combinations. He would self regulate, he would think, it was just amazing.
Then my other event horse, Vodka - He was the opposite. He was a very highly strung and individual boy, with talent up the woozah. In SJ, he would just rock back into this amazing canter and jump the round like he had been studying it his whole life.
Out on CC, I had to drive for all I was worth up into my hands to shorten him so he would sit back and think about the jump. But boy that horse could jump.
I guess my point is that all of this is different depending on what horse you are on. There are horses out there who would get you around a course no matter what position you are in - And there are horses out there who need that support 100%.