I think it depends on the type of business. Our model was retail so didn't require a critical mass of users or a repeat behaviour. We knew customers loved our product so the challenge was to finding ways of reaching more IG users. If you have a risky and expensive to test hypothesis, I imagine big growth will be something you'll look for to validate whether it's a worthwhile pursuit.

That said, most startups experience plateaus and dips. These are the moments that truly test the fortitude and resolve of the team.