Deconstructing Startup Growth
The most important element is having a large percentage of users who consider your product a “must have” (over 40% is a good benchmark). This gives you two key benefits:
The first is that your churn will be relatively low (if it’s a “must have” why would users leave?), so you won’t be wasting resources filling a leaky bucket. The second is that “must have” products generally maintain strong word of mouth.