From the summary of a report by the Government Accountability Office (GAO):
The Social Security Administration (SSA) selects cases for continuing disability reviews (CDR) using several inputs, but it does not do so in a manner that maximizes potential savings. SSA first prioritizes CDRs required by law or agency policy such as those for children under 1 year old who are receiving benefits due in part to low birth weight. Then SSA uses statistical models to identify the remaining CDRs to be conducted each year. The models also determine which cases will receive an in-depth review of medical records by the Disability Determination Services—the state agencies that conduct CDRs—versus a lower-cost questionnaire sent directly to the beneficiary. As shown in the figure below, a growing number of cases have been set aside for future review (backlogged) over the last 10 years. Although SSA somewhat considers potential cost savings when selecting cases for in-depth reviews, its approach does not maximize potential savings for the government. For example, estimated average savings from conducting CDRs are higher for some groups of Disability Insurance (DI) beneficiaries than others, but SSA's selection process does not differentiate among these groups. As a result, it may be missing opportunities to efficiently and effectively use federal resources.
I would characterize Social Security's response as being "GAO, to the extent it's practical, we're already doing everything you're recommending."
My response is "GAO, you're picking at nits. The real problem is that the agency has been so badly underfunded that it's unable to work down its backlogs."