Reiterating my earlier point about how startup methodologies are no substitute for skills, here's a great article by Steve Blank attacking a dumb application of his own Customer Development approach:
But he was missing the bigger picture. The idea of the tests he ran wasn't just to get data - it was to get insight. All of those activities - talking to customers, A/B testing, etc. needed to fit into his business model - how his company will find a repeatable and scalable business model and ultimately make money. And this is the step he had missed.
Methodologies like Lean or CustDev are no substitute for experience. They can complement experience to make it that much more effective, but ultimately without the underlying experience, they are as useless as a master chef's recipes might be to someone who's never even cooked an egg.