“We do agile – we don’t plan” – this was the agile ‘slang‘ in early days when agile transformation was starting. For some persons, it was a motivation to escape from constantly repeating the lengthy project anatomy sessions – perhaps for me too.
Just to quote the well-known sentence from Dwight David Eisenhower
: “Plans are nothing; planning is everything“. Some agile coaches would further say that a long term plans and long term commitments are irresponsible and unprofessional behavior! Long term plans go exactly to the opposite of Lean thinking: deciding too early, no constant focus on the highest possible value through prioritization, delaying to deliver value frequently, not having potentially shippable product often, questionable incremental development of value and iterative learning and improvement…and many more.
What is the most sad of all – process forces people to commit to something that is unlikely to happen which violates the basic human respect and represents a source of many conflicts between the “line management” and project management.
Therefore, a true incremental and iterative development on principles of continuous improvement limits planning and commitment to a small chunk of time where requirements are fairly known, impacts of external ‘surprise’ factors are limited and they don’t influence planned outcome to the large extend. Each of iterations moves us closer to the wanted product. It makes our planning gradually less wrong – thus more predictable within the range of uncertainty as shown on the example:
 34th US president winning 2 mandates 1953-1961