Recently I've been thinking about something I affectionately call Tustain's Law. It's something a friend of mine was fond of saying: "If you make something twice as easy, it becomes ten times more useful."
You can argue the numbers of course, but the insight is clear - making something easier to use doesn't just mean your users will have a nicer time; often it means that ten people are trying to engage with what you've built, and nine of them will give up in frustration unless you're actively designing with them in mind.
Ten times more useful reminds me of the first pair of Bluetooth headphones I owned. They always had connection problems. It was rare they'd connect first time, and because they were unreliable I didn't get much value out of them. The headphones I own today are functionally identical objects - similar sound quality, similar battery life - but because they always work they slip into my unconscious and have become a permanent part of my life. I use them for at least 40 hours a week and I don't leave the house without them.
Tustain's Law means user-friendliness isn't just a nice-to-have. It's not a luxury to be tacked on if there's time at the end of the sprint. It's actually fundamental to how valuable what you make becomes. It changes the way people engage with technology, moving it from "if I really have no choice" to "it's my go-to tool". In many cases, "10x more useful" would be a conservative estimate - it's probably closer to infinitely more useful. The difference between using it or not.
Paul Tustain, the man behind Tustain's Law, was killed last week in a tragic motorbike accident. He was a brilliant man, easily the smartest CEO I've ever known, and a good friend who profoundly changed the course of my life.
Maybe in the coming days I'll face writing up a proper obituary or something, but for now this is all I can manage. And it's a pretty good start - if you're following me you're probably into technology, and knowing Tustain's Law might help you make what you're working on ten times more useful to people. That might help you change the world, or at least your corner of it. And if it does, then Paul has had a profound effect on your life too...
Paul Tustain, 1962-2025. Rest In Peace my friend.