Toyota Motor Manufacturing USA, Inc. (TMM) encountered product proliferation problems with defective seats due mainly to the company's deviation from its normal production plan and lack of a recovery system. In April 1992, TMM's run ratio dropped from 95% to 85%, meaning that 45 less cars were being produced per shift, which in turn translated into overtime for the workers. As a result, too many cars needed off-line operations of one type or another before they could go on …showed first 75 words of 1611 total…

…showed last 75 words of 1611 total…in a prompt, complete, and systematic matter. This is so because true needs would deviate from a production plan unpredictably, and also because shop floor problems were inevitable and would crop up constantly, in turn making deviations from planned operating conditions unavoidable. Any departure from the aforementioned method of handling exposed problems would paralyze the plant, leading to problems like that of the defective seats, hence the need for exercises such as the "Five Why's."