Comment by eternityforest

Everyone has an individual level of random line noise.

There's a whole field of human factors engineering that seems to agree "just being careful" is not a reasonable strategy by itself.

I have one brain, and the world contains multiple objects, which exist at the same time and don't take turns in an orderly fashion.

There will always be something I'm not consciously focusing on, and there is large individual variance in how well people can do things automatically.