Being an IT company running a service desk for a customer we have tended to use ITIL (IT Infrastructure Library, a set of 'Best Practices' from OGC) in management of the IT support work. A key factor of ITIL is that when an issue (with no known cause) is reported by a customer you don't try to identify the underlying problem, you just find a workaround or fix and apply that to get the person working as quickly as possible. You may if an issue is occuring regularly put it into problem management and try to find the root cause and solve it, but how often you will do that depends on your definition of regularly (multiple times a day? daily? weekly? monthly?).
Lean on the other hand seems to take the opposite approach and expect that when a problem arises it will be analysed, the cause found and a solution put in place if at all possible.