Missing the signs
This commercial building recently lost its entire first floor to water damage. I used the drone to photograph & video the damage on behalf of the insurance company after the event. Regular drone inspections are low cost and it would have been easy to see months ago that the gutters were blocked and would cause a problem (there are actually saplings growing in the leaf mulch up there). No costly scaffolding was required for our inspection, nobody was at risk aloft and minimal flight time was involved.