The FAA in all my experience allows for one problem free flight leg then a new MEL can be issued. If you do not fly one flight leg W/O the defect repeating the MEL control number remains the same as well as the original drop dead date.
Most airlines under the FAA define a chronic discrepancy for intermittent problems as 3 PIREPS within a specified time frame. It is often a gray area topic as to the depth of troubleshooting required but the FAA usually likes to see a "positive fix" after the 3rd time, not just "R&R'd FCC ops ok", they like to see "found pushed back pin in rack plug XX, fixed and test's good"