I reuse quick links, missing links, etc. for the life of the chain it's fitted to. On and off around 5 or so times for cleaning, maintenance etc. Keep an eye out for wear on the pins (I've never seen any signs of wear so far) and a tiny dab of grease when re fitting.
Official advice is no, single use only. Can recommend Wipperman Connex quick links - designed for multiple re-use and very easy to assemble/disassemble.
KMC ones for me also. One quicklink comes with their chains. I typically only use a new one when I change chains, and they are split multiple times during the life of the chain
Posts
https://www.amazon.co.uk/Sram-Chain-Speed-Powerlock-Connector/dp/B009F96WK4
I used just one link so far, about 40 to 50 times. It's still as good as new.