Did they ever reuse the payload fairings of the Falcon 9?
There are a few related questions about maximum reuses and fastest refurbishment that might be asked later I guess
They have according to the linked article done so on three launches. This is coroborated by videos on youtube, among then from everyday astronaut.
For good statistics on things like this that change every mission, check out SpaceX Stats
At the static moment I write this, 4 reused.
SpaceX has a huge manifest of missions for Starlink, since even at 60 satellites a launch the full constellation of 4400 satellites is going to take a ton of launches (74 minimum! Almost as many launches as they had done in total before Starlinks first launch).
Their goal is to reduce launch cost for Starlink, even if it means slightly increased risk. (If you are building 4400 satellites, how much does it matter if you lose 60 once in a while).
Expect them to leverage this experience in reducing internal costs through reuse to reduce costs for commercial customers.