For some time we had encountered a number of flat tires. One nail, one shard of glass from a bottle, others. Someone voiced suspicion of intentional sabotage. Then I found two more nails lying around that dispelled suspicions: One rusty old nail in the driveway, in a place where it would naturally occur falling out of decades old fencing. One shiny new nail in an expansion joint in the parking area at the gas station. An employee mentioned “I always find some when I clean up. They fall off trucks of people going to work.” One in tire plus two found added up to three nails in one month.
Deal with stuff as it happens.