An interesting look at how long lead times from idea to specification to implementation to release can cause waste in the software development process.
The time it takes from idea to delivery should ideally be as short as possible to provide the most benefit to the end user and keeps a software development team focussed on the task at hand. Dispersing focus too much or keeping old descriptions around that may be out of date or irrelevant by the time the developers get to them causes significant waste in terms of programming effort, focus and mental capacity.
Agile development teams partially work around this by defining the tasks to be done for a few weeks into the future, close to where they are being worked on. The team should always thing as a whole, whether the particular request still makes sense at this time or if it needs to be re-assessed.