That little things can make a big (sometimes VERY big) difference. Two examples:
Example one: Jared Spool wrote a great often-cited essay about the $300 million dollar button, which I will summarize: A major online e-retailer (I suspect Amazon) redesigned their checkout process by changing ONE BUTTON and adding a brief message. Sales went up $300 million in the first year.
The essay is here: The $300 Million Button
Example two: The B-17 Bomber was being built by Boeing for the US Military in 1935 and it was considered a death trap and "unflyable"… The first two test flights ended up in crashes, killing both pilots. The government was about to cancel the contract but the next pilot came up with an idea.: A checklist for take off and landing. Simple, obvious in hindsight, but it made the "unusable" B-17 Bomber a plane that could be safely flown and landed. The B-17 went on to help the Allied forces win World War II.
This is recounted in the great book The Checklist Manifesto: The Checklist Manifesto: How to Get Things Right