The FDA said Saturday that it reissued an emergency use authorization to Quest Diagnostics to use its COVID-19 test with pooled samples. Pooling works best with lab-run tests, which take hours -- not the much quicker individual tests used in clinics or doctors offices. Thats because the logistical and financial benefits of pooling only add up when a small number of pools test positive. Experts generally recommend the technique when fewer than 10% of people are expected to test positive. For example, pooling would not be cost-effective in Arizona, where a surge has pushed positive test results to well over 10%.