Would you mind sharing the age of your kids when you started this approach?
At first I did it with cash and they didn’t have bank accounts, but I found the problem was the younger one would “misplace” his savings money all the time. And I also found that the ADHD was sly and would “find” the younger brothers misplaced money and spend it, but in such a way that I couldn’t prove it. So I just went and opened bank accounts for them. Who has cash these days anyway! It’s been much better since.