A paved surface fails at the joint long before it fails at the block. The blocks themselves are 35 to 50 N/mm² and will outlast the people who laid them; what settles, rocks and eventually cracks is the bed and the sand between the units.
Bedding sand should be sharp, washed and consistently graded, laid 25 to 40 mm thick and screeded — never compacted before the blocks go down. Compacting the bed first removes the very compliance that lets each unit seat itself under traffic.
Joint filling is the step most often skipped. Interlock is not a property of the block shape; it is a property of a completely filled joint, 2 to 3 mm wide, brushed and vibrated until it takes no more sand. A surface vibrated once and left is a surface that will loosen over its first winter.
Compact in two passes with a plate compactor on a rubber mat, brushing more sand in between. Then edge-restrain every free edge. A paved area without a restrained edge unravels inwards from the perimeter, and no amount of joint sand will stop it.