TheCodeBreakers
This tortuous method—for some reason they failed to heed the
writings of foreign cryptanalysts on solving this system—suggests why so
little information was extracted from the strip cipher. The Tokumu Han
kept increasing the size of the section in its American branch that
handled strip messages until there were about 40 officers, 10 enlisted
men, a dozen typists, two dozen women clerks,
Professor Yamanashi of the Navy War College, and a mathematician,
Ozaki. Though efforts were continued up to the end of the war, the life
had long since gone out of them; the Tokumu Han, considering the strip
cipher unbreakable for all intents and purposes, vacated its hopes for
crypt-analysis and looked instead to traffic analysis as its chief source of
information.
The difficulty with this, as Lieutenant Commander Satake put it, was
that "Our whole analysis was based on probabilities; there was nothing
of a definite nature
annaabi.ee 
