Doesn&#x27;t shiva2012 specifically address this in his point?  You are describing a slow drift that would accumulate over many days and eventually lead to an error, but that is avoided by regularly re-syncing the clock on the satellite and the ground (&quot;clock drifts dealt with via regular ground synch&quot;).  In a hypothetical world where Einstein didn&#x27;t figure out GR, nor the thousands of physicists who followed him in the intervening decades, the implication for GPS would be an unexplained drift that would be easily correctable though still mysterious.