I have been working as a software consultant for more than 11 years. Because of that I am an eager supporter of lean principles and agile methods.
The reason for human domination on this planet is our extraordinary ability to adapt to change. But why do we try to fight this ability within software development?
Only changes in the near future can be predicted, for the rest we have to adapt and overcome, like soldiers. Any change, even a small one can invalidate a whole plan. A goal however, is more stable and can survive even major changes. That is why an agile team must strive for a goal, not a plan, while responding to changes on the way to the goal.
The Horizon of Predictability is the distance into the future that a team can be reasonably sure that plans will be stable. Any further into the future plans start to get uncertain and even further the future becomes totally unpredictable.
The horizon of predictability varies depending on the environment, but is for most IT organizations not more than 30 days, i.e. the iteration length of a Scrum sprint.
To minimize the overhead in short iterations consider automating your environment e.g. continuous integration, daily builds and automated tests.
Read more here:
Change is constant - blog post at Agile Advice
The pros and cons of short iterations - blog post at Agile Advice
How long is a time box? - blog post at the Pragmatic Architect
Predictability Paradox - whitepaper by Mary Poppendieck