I've found two switches in a panel to be reasonably memorable, three in a row to be just over the border into confusion, and four or more right out. Fortunatel

I've found two switches in a panel to be reasonably memorable, three in a row to be just over the border into confusion, and four or more right out. Fortunately, all the places in my home that had more than two were places where you could control both interior and exterior circuits. My solution was to use black switches for the exterior lights and white for the interior. Like, a single panel might have a black and two whites, or a pair of each. I find it much more intuitive that way.