An integrated circuit improves scan testing efficiency by addressing slow Scan-OUT pins. The integrated circuit shifts data through high-frequency Scan-OUT pins every cycle and through low-frequency Scan-OUT pins every other cycle. Data that cannot be shifted through low-frequency pins is stored in an accumulator and later shifted out through high-frequency pins. Despite changing the scan-out data pattern, the tester used for testing the integrated circuit anticipates the resulting pattern, providing for the testing to not be negatively impacted.