space X reuses Falcons a lot.

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https://www.designnews.com/design-hardware-software/spacex-reveals-3d-printed-rocket-engine-parts

SpaceX's first 3D-printed rocket engine part already launched on the Falcon 9 rocket in January for the THAICOM 6 mission. One of the rocket's Merlin 1D engines contained a 3D-printed main oxidizer valve (MOV) body. The valve operated correctly with high-pressure liquid oxygen, withstanding high vibration and cryogenic temperatures. The printed valve body has better strength, fracture resistance, and ductility than a part made with traditional casting, as well as lower variability in material properties. It was also a lot faster to make, being printed in two days instead of several months. The valve is now qualified to fly on all Falcon 9 flights.