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It's a cost benefits analysis. Medicine does this, and is constantly updating their recommendations for screening based on the data that comes back. For example, it used to be recommended that all women perform a breast self exam every month, then data showed us this didn't prevent cancer and actually caused harm because it lead to needless surgeries and biopsies. (Sources here: http://en.wikipedia.org/wiki/Breast_self_exam)

Things like Prostate-specific antigen screening of healthy men is no recommended by the United States Preventive Services Task Force because "the potential benefit does not outweigh the expected harms." (Source in: http://en.wikipedia.org/wiki/Prostate-specific_antigen)

The jury is still out on mammogram screening of healthy women for breast cancer. (See: http://en.wikipedia.org/wiki/Mamogram)

The Cochrane analysis of screening indicates that it is "not clear whether screening does more good than harm". According to their analysis one in 2,000 women will have her life prolonged by 10 years of screening, however, another 10 healthy women will undergo unnecessary breast cancer treatment. Additionally, 200 women will suffer from significant psychological stress due to false posivitive results.[10] Newman points out that screening mammography does not reduce death overall, but causes significant harm by inflicting cancer scare and unnecessary surgical interventions.[11] The Nordic Cochrane Collection notes that advances in diagnosis and treatment of breast cancer actually may make breast cancer screening no longer effective in decreasing deaths in breast cancer, and therefore no longer recommend routine screening for healthy women as the risks might outweigh the benefits

This is why we use science and do studies and always question if we are doing the right thing.