On average how long do you guys stay with a startup project before you deem it to be a failure?

Some context to this, I’m working on a big project of mine called Deapwork its gear towards the productivity niche and people who struggle with procrastination. I want to know how you guys go about stoping a project when you’ve essentially hit nothing but dead ends. Is it 3 months? A year? I’m hoping deapwork will be a success but I’d love to hear your frameworks on when to put an end to something thats not working. Also let’s follow each other I love to make new friends!!