There is a lot of talk about the idea of achieving Product-Market fit. Successful entrepreneurs such as David Cummings discuss this topic regularly on his blog.
Achieving product-market fit is one of those things where you can’t always define it, but you know when you have it. My view is that when your company has brought on 5 new consecutive clients for the same product and for the same value proposition, then you most likely have product-market fit.
Startup Lessons Learned 