Honestly? Who has time to rewatch a series??
For me that’s Buffy and Babylon 5, both three times. I think Queen’s Gambit may beat them, but I’m not there yet.
Futurama, Scrubs but if it counts, then number 1 would be the first 6 or so seasons of The Simpsons.
If you rewatch scrubs make sure to torrent some seasons with the original music. Anything up on a streaming service won’t have it because they didn’t buy good enough music rights to include streaming and all the songs Re replaced with stuff that’s not nearly as good/fitting. Makes a huge difference in the show IMO.