Of course spending ten years on a project increases your chances of success, but that's missing the point. What is interesting is that it has to increase by 1000% in relation to starting ten projects in ten years.
I don't think it's missing the point. I brought up the extreme example of switching every day to show that the math is specious.
I think the math works, but the difficult part is what the minimum amount of time needed to know if you're going to succeed or fail. If you knew that, or even in the ballpark you'd have something you could apply. Otherwise it's hard to say if a day or a year is a better measure.