These days, people create web apps in a week, two days, or even in 24 hours (Red Bull not included). The key is not the span of time assigned to it. Users won't flock to your app just because you built it quickly. The essential common point between all those posts is to build a functioning MVP within a fixed and very limited time, which forces you to be ruthless about the scope.
In this article, Laurie Young details his approach and results for building HabitualApp (an app designed to help you stick to your new year resolutions, based on the theory that if you do something every day for 30 days it will stick). One of the key points:
(...) I realised that getting traffic to the site was going to be harder that I thought. My ideas of just building an app and letting the traffic build up totally on its own was going to fail if no-one at all ever saw it.
This is something that every developer goes through when they try building something from a technology-focused point of view. My view on this is that it's better to look at what delivery channels you have available to you, and build something for that "audience", rather than start with the product and then look for users. If you're a proficient developer, getting users will be an order of magnitude more difficult than building an app.
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