You are so wrong certain angles will put more stress on parts of the muscles in the early days I never had a good quad sweep and I started to do my front and back squats with legs close together and I saw improvements in the quad sweep I am shocked that somebody who has being lifting as long as you have dont know this.
muscles respond to intensity, a quad for example straightens the leg, straighten the leg under tension and it will respond and grow, the shape it grows is determined by its genetic shape and insertions.
If you got results then you just worked the muscle more intensely.
I bet you think you cant get good legs just by doing leg extensions as opposed to squats