Musk said Thursday that the previous version of the Falcon 9 could be refurbished in about 10 days if necessary, but that preparing it for upward of 10 uses would have required a "fair amount of work between each flight." Block 5 is intended to reach 10 or more re-flights without scheduled maintenance — in essence, by simply moving the rocket from its landing spot, refueling it and then putting it back out on the launch pad.
Source: Los Angeles Times May 10, 2018 18:36 UTC