Doneas
I love how brutally simple this is. We've got thousands of founder tools out there, and people are still paying for a phone call with another human being who asks "did you do the thing you said you'd do?" There's something almost old-school about it, like Weight Watchers for startup execution. The group size matters too. Three or four people is small enough that you can't hide, but big enough that you're not just talking to a mirror.
The daily part is what makes or breaks it, honestly. I've seen so many accountability groups fizzle out because they meet once a week and everyone just paper-overs their lack of progress. A daily call forces you to either make progress or confess you didn't, and there's nowhere to hide in that confession. I'd want to know how they handle time zones and travel days, because those are usually where these things collapse.
What gets me is the restraint. No gamification, no leaderboards, no points for streaks. Just a calendar invite and the quiet terror of letting two other founders down. That might be the most effective productivity system I've seen all year.