How do you use waitlists for your startup ideas?

I’m working on a project focused on helping people build and manage waitlists for their startup ideas or businesses. I want to understand how others approach waitlists, whether you’ve successfully used one before or considered it but decided against it. If you’ve built or thought about building a waitlist, I’d love to hear about your experience! Here are three questions I’m especially curious about: 1. What made you decide to use (or not use) a waitlist for your project? 1. If you did build a waitlist, what was the effort required and what tools were used? What conversion rates did you obtain? 2. How did you keep people engaged after they signed up, and was it worth the effort? 3. If you didn’t go forward with a waitlist, what stopped you? Lack of tools, time, or something else? I’d love any advice, stories, or lessons learned. Thanks in advance for sharing!