This is the big flaw i see against Keynes, that the political discipline and foresight it takes to pay forward is very hard. Instead it becomes another round of the too much debt cycle. Unfortunately I don't have any alternative. (many would put their pet economic hobby horse here)
Edit: I noticed a problem with my comment, I said pay forward but Keynes has a pay back what you borrowed earlier.
[0]: https://www.wsj.com/articles/jerry-browns-legacy-a-6-1-billi...
The key argument for approval voting - right here.
http://www.latimes.com/opinion/op-ed/la-oe-jackson-californi...
http://webcache.googleusercontent.com/search?q=cache:nQgta5-...
If your state is debt-free, that's great; you have X years to borrow and spend your way out of trouble. If your state owes even $1, better pay it off quick to reset your Keynesian pump-priming capacity! And if your state can't pay off its debt, the younger generations aren't forced into austerity to pay for the excesses of the elders.
Lending terms will tighten up as the jubilee deadline approaches. If it's only 5 years away, lenders will not even bother calculating payoff periods further than 5 years into the future, minus the amount of time required to file and collect on any lawsuits for nonpayment.
If a state actually hits a jubilee with debt still on its books, it will quickly find that borrowing becomes a much weaker tool in its fiscal toolbox. It might also help to make all persons holding elected office with budgeting or spending authority at any time during the state's indebtedness to become ineligible to hold such offices for Y years after a jubilee.