While I am not a success story yet, I am a founder. If my clients had a problem on their site, sometimes I would just fix it for them instead of showing them how to do it themselves. Then I would improve the system on the next update so I didn't even have to show the user how to do something because I made it super obvious.

Long story short, instead of making documentation, I fixed everything that my clients would ask me how it worked. This has limitations, but it saved me tons of time on support, training and documentation that would later change anyway. And my product got consistently easier to use, and dropped training requirements to near zero.