When FDR ran for president in 1932, he had no idea what to do about the Great Depression nor any ideological axe to grind. He was just a skilled politician who wanted to be President.
When elected, he adopted a purely pragmatic approach.
something. If it works, do more of it. If it doesn't work, try
something else." Unfortunately, this is not how it worked out.
Whenever the government starts a spending program, the program
develops a dependent constituency who will fight to preserve that
program regardless of whether it serves its original goal. So in
practice the New Deal became,
"Try something. If it works, do
more of it. If is doesn't work, do more of it."
A classic example of this is the Brownsville shuffle.
In the early sixties, someone discovered a loophole in the oil import quotas. They would ship oil into Brownsville by tanker, pipe it into Mexico, then pipe it back into Brownsville. Since this fell into the category of "oil imported for immediate export" and "oil exported for immediate import", it was not covered by the quotas.
Later, when the oil quotas were abolished, a proviso was added that all oil from Mexico must be offloaded at Brownsville before being piped or shipped to its final destination. It seems that there were so many jobs dependent on the shuffle, they were able to preserve it.
By any reckoning, the shuffle was a mistake. It was not intended, or even foreseen, by the legislators. It served no useful function, wasting time, money, energy and product. Yet, like all of the government's mistakes, it was preserved in perpetuity by its dependent constituency.
The only thing the government learns from its mistakes is how to
cover them up.