Tends do get completely obscured and you're back to mental diffing. I know, I know, nothing a bigger checkbox could not solve, but they look weird when you only make them bigger horizontally.
True. Ideally you put some "event received" indication across the whole trigger area, e.g. that little Android ripple animation. Certainly does not hurt to do the same (whole area clickable, and with visual feedback) even when your designer insisted on fashionable slider-toggles.
Subtle things like that greatly reduce the mental background load for the user, but that's impossible to quantify. Chances are you don't consciously notice when it's missing even when in theory you are fully aware of the concept.
