So apparently there's some debate that Shingo was just a bloke who popped in to Toyota every now and then Ohno was busy inventing the Toyota Production System (which went on to become labeled as "Lean").
Does any of this matter? Um, no, not really. The fact is that Shingo's undeniable contribution was in the field of reducing set-up (changeover, makeready, etc) times from literally days to less than nine minutes. And without that, you just can't do the rest of Lean, because you'd have to carry stock, make proposterous economic batch sizes, and generally remain focused on yourself, rather than the customer.
It was this realisation that made us decide that one of the key areas to focus on is set-up time. Following this doggedly to Shingo's target of nine minutes or fewer provides huge paybacks, often out of all proportion with the effort expended.
I'm sure its important to get a historically accurate view of who did what at Toyota 50 years ago. But for most of us, just applying the tools is enough reward!