True or false?

When bluffing, or value betting the river, we usually want to target the middling hands in our opponent's range with our sizing (make middling hands indifferent as opposed to strong or weak hands), as they occur more frequently due to a normal distribution style curve, thus maximising our EV vs their range?

It's always confused me why we target 'bluff catchers' with our sizing on the river, and the above suddenly occurred to me in a light bulb moment.

I'm probably talking bollocks though, as per usual.