Err, so there was an erroneous decade where we tried to do better?
The mid 50s-60s were a discrepancy in american history in a multitude of ways, so I'm not sure that I'd consider prison reform any different in that regard.
I also wouldn't consider a decade as representative of the american justice system when we have plenty of evidence that it's not representative of either the past (where we used to just hang people after three strikes) or the present (where, as you noted, we have three strikes laws).
In fact, it seems as though once a century we'll have a decade where they half-heartedly try to implement rehabilitative reforms, keep at it for maybe the better half of a decade, and then act shocked that it hasn't decimated incarceration rates yet. Shockingly, it takes longer than a few years to reform a society.