I am a firm believer in allowances. When our children were young, they were given a certain amount of money each week. They had to give their own ma’aser, they had to save a percentage and the rest, they could do what they wished. Some of our children hoarded every penny they got, and some spent it all. But they all learned that an allowance was never enough and they all learned to look for jobs to supplement their allowances, according to their time constraints.
When our kids were in seminary. We began with no allowance. They had to write down every penny they spent for the first month (after the Chagim) and we reviewed the amout spent, where & when and then we gave them a “firm” monthly allowance. Anything over and above said allowance needed our approval.
When they were in college their allowances were dependent on their schedules. If there was time to work, they had to work. If their workload was very heavy, they were not allowed to work and we paid for gas, books, clothes, etc. We tried to be very fluid, but they were always accountable for what they spent, if we gave them the funds.
As adults, our children are (for the most part) very responsible and careful with their money. They would never live over their income and only spend what they can.
However, try as you might, there are always individuals who simply will not live within a budget no matter what their age, and they always have monetary issues.