I don't believe that time fixes it. Time - if anything - makes things worse. The real productive capacity of our nation - our people, and our real capital - doesn't get better by being wasted. People lose skills if they don't use them, and factories and machines don't improve from sitting idle. To the extent that people and businesses are attempting to improve their balance sheets by increasing savings and paying down debt, unemployment only makes things worse. And if people react to unemployment by spending less and saving more (a perfectly natural reaction), that simply drives the economy further into the ground. Since private savings and debt net to zero, only government can create financial savings for the private sector and reduce private sector debt, and only by spending more than it taxes - in other words, by running a deficit.
The Great Depression lasted ten years, and it wasn't until government deficits reached 30% of GDP - during WWII - that it finally ended. (By comparison, current deficits are about 9% - and New Deal deficits ranged from 0% - 6%.)
As far as long-term is concerned, it's worth noting that all that WWII debt had no lasting harmful effects at all. WWII just caused us to do what we could have done ten years earlier, without having to have a war.