I don't like that as an incentive. For a start, it keeps your children in your financial orbit for the rest of your life. Secondly, it communicates to your children that you don't expect them ever to make as much money as you did.
Whenever I wish I were super-wealthy, I try to remember that super wealth probably just creates all sorts of problems when raising children. If I ever do get super wealthy I'll plan to spend all but a few million dollars, secretly and out of sight of the children, before they reach the age of twelve, so that I don't have to worry about them growing up with the typical rich-kid problems.
He's actually even more tactical than that. The multiple depended on the job his kids get. I think he said he'd quadruple a nurses salary but they wouldn't get anything at all if they became investment bankers.
"I want to leave enough money to my children that they can do anything, but no so much that they will do nothing".