Jim Collins has a helpful metaphor on why this assumption is wrong. He calls it the flywheel principle.
Imagine a huge flywheel. It weighs 5000 pounds. It is 2 feet thick and about 30 feet in diameter. Your task is to get the flywheel spinning. You put a shoulder to it and after two or three hours it makes one rotation. The second rotation in one hour less. The third rotation is even quicker. Each rotation of the wheel moves more and more quickly. Momentum is your friend. Jim Collins says:
Then, at some point—breakthrough! The momentum of the thing kicks in in your favor, hurling the flywheel forward, turn after turn … whoosh! … its own heavy weight working for you. You’re pushing no harder than during the first rotation, but the flywheel goes faster and faster. Each turn of the flywheel builds upon work done earlier, compounding your investment of effort. A thousand times faster, then ten thousand, then a hundred thousand. The huge heavy disk flies forward, with almost unstoppable momentum.
Now, suppose someone asked, “which push of the flywheel was the key push?”
There was no one push that made all the difference. Successful change agents know it takes 1000 tiny pushes to create a change.
People often ask, “What is ‘THE KEY’ to church growth?”
My answer: “THE KEY to church growth is realizing there is no one key to church growth.” Changing a church to becoming a vital, vibrant, growing church is about a thousand little changes.
 Collins, Jim (2011-07-19). Good to Great: Why Some Companies Make the Leap…And Others Don’t (Kindle Locations 2757-2760). HarperCollins. Kindle Edition.