There are common areas and then there are zones where people park stuff. I've tried to get my SO to put stuff I leave in private areas in one of my zones, rather than putting it somewhere I will never find it.

It's also a battle because of the clutter, 10% of it is mine, and I never move their stuff.

The problem comes in when there's something that could reasonably be trash (usually a box that I might need to return something) gets tossed. :(