Been listening a lot to KEXP lately, and this week they have been running a continuous "Six Degrees" week, where every single song they play has some kind of link (musician, producer, cover version, whatever) to the previous song. It's incredible. Earlier I heard a DJ, over several hours, move song by song from Einsturzende Neubauten to Boys II Men.
@jimbob Radcliffe and Maconie have been running a listener-suggested daily linked chain and they're up to 8771 songs now. https://thechain.uk/ Not sure if its still going, no dates there :(
The Chain

A searchable database for BBC Radio 6 Music - Radcliffe and Maconie's The Chain, officially the longest listener-generated thematically linked sequence of musically based items on the radio.

The Chain