The nature of the varying cyclic output can be quite jarring, or it can be nuanced and smoothed out:
Now, along comes Agile, and my thoughts go back to the oscillator. And, I'm not the only one. Jim Highsmith has been thinking about the same thing. The architecture (stucture and behaviors) of all agile methods includes feedback, mostly from customers/users, but also from sponsors/stakeholders. The mandate for agile teams is to respond, and be responsive, to feedback. That is, a sample of output--in the form of user experience--becomes a part of the input to the deliberations of the agile team.
Now, if the feedback is phased (timed) one way, it will stablize the iteration. Change the timing a bit and it will destablize the iteration and cause oscillations. In effect, the team builds one thing, only to find out--in the wrong timing--that the customer has changed their mind; the team responds to the change. But, meanwhile, the customer is experiencing the wrong (earlier) thing and seeks correction. Ooops! the team is driven back, or a different way.
If the timing is never corrected, the iteration becomes oscillatory and really nothing gets done.
Time for the project manager to step in and call a halt and dampen the oscillations. Everyone needs to take an Iteration 0 break to do a little reflection and get the timing reset. Maybe a spike needs to be inserted to allow for some non-deliverable prototyping or modeling.
In any event, oscillations can not be allowed for more than a cycle, perhaps two. If not naturally damped out, the PM must take action!