What made The Wörgl Experiment successful?
It was successful because it combined three things at the same time.

Firstly, it increased available currency at a time when currency was scarce for any but the rich - so everyone was more solvent.

Secondly, it had a negative interest rate, so the encouragement was to spend quickly.

And thirdly, it was a local initiative, and belonged to the town, at a time that was particularly introspective - isolationist, even.