Show HN: Seven39, a social media app that is only open for 3 hours every evening

It's an interesting idea, but if it's only open at a convenient time for a particular group, it's going to lack diverse and worldwide perspectives, and those are important for building a welcoming ecosystem. I doubt giving each timezone its own 3 hours would work, but perhaps rotating the 3 hours each day so that it's anchored on a different timezone would encourage that diversity of content and perhaps even encourage creating connections across timezones.

That said, if you've had success with it in a friend group, perhaps that suggests it's a nice mechanism for a group chat app, rather than for a public social media site?

I kind of like the idea of a regional social media app which literally doesn’t work in other parts of the world. It makes the space a little more special than something trying to reach everyone IMO

At the extreme level of “regional”, that’s Nextdoor.