My next collection mints in hourly auctions, and doesn't have a fixed end date or token supply. Rather, the collectors will decide when the collection ends.
https://medium.com/@lawrence.x.rogers/thehours-duration-token-count-a57011f7ec76

Experimenting with on-chain art NFTs || Creator of Jackson NFT and MergeFlowers. 
www.lawrencexrogers.com
www.thehours.art

Each auction, the probability of a "Finishing Touch" action increases. If this action wins, then the collection will end.

shoutout to Stanford CS109 for coming in handy IRL https://i.imgur.com/RjiSZ99.png

The probability will increase quadratically over time, but the rate of the increase is a question I'm posing to the community.
https://discord.com/channels/997241347553628190/998723511545774111/1080937724330119259