There are a lot of great stories out there to illustrate this, but I was reminded of this blog post from a former Microsoft programmer. Joel Spolsky described what it was like to walk into a code review and see that Gates had decided to sit in. Spolsky wrote a 500 page spec for a new macro language in Microsoft Excel (which would eventually be released as Visual Basic for Applications), and the next day. Not only was he surprised to see Gates, but to see that the boss had come prepared.
He sat down and exchanged witty banter with an executive I did not know that made no sense to me. A few people laughed.
Bill turned to me.
I noticed that there were comments in the margins of my spec. He had read the first page!
He had read the first page of my spec and written little notes in the margin!
Considering that we only got him the spec about 24 hours earlier, he must have read it the night before. He was asking questions. I was answering them. They were pretty easy, but I can't for the life of me remember what they were, because I couldn't stop noticing that he was flipping through the spec...
He was flipping through the spec! [Calm down, what are you a little girl?]
... and THERE WERE NOTES IN ALL THE MARGINS. ON EVERY PAGE OF THE SPEC. HE HAD READ THE WHOLE GODDAMNED THING AND WRITTEN NOTES IN THE MARGINS.
Here's a guy who's the CEO of a huge company, the richest man in the world, and still he spent his night reviewing this guy's software spec. I'm sure that that sort of relentless attention to detail wasn't the only thing that made Gates so succesful, but I'm sure it didn't hurt.