Depending on usage, a certain percentage of stones will come loose over time. Depending upon your tolerance for loose stones, maintenance in the form of patching and / or roll coats will be necessary.
Public spaces will require more frequent maintenance.
Over time, a certain percentage of stones will come loose. Typically, about 1% of stones will come loose annually and this rate will increase with pedestrian or vehicular traffic. If the installation is located in a public space, the rate of loose stones will be even higher. The use of bikes, skateboards, roller blades, wheelchairs, luggage with wheels, shopping carts, etc. will increase the rate of loose stones. If there is patio furniture you may notice an increased number of stones coming loose where people pull in their chair and it drags across the surface of the pavement. Even high heeled shoes can cause additional stones to come loose.
In the event of vehicular traffic (golf carts, forklifts, snow plows, lawn equipment, cars, etc.) a greater percentage of stones will come loose due to the pressure and traction of tires gripping the surface, especially where tires turn.