The selection of the iteration length should be guided by the following factors:

• The length of the release being worked on.

It means that if the team is working towards a release which is three months away, one-month iteration will give only 2 opportunities to gather feedback which in most cases insufficient.

The general rule of thumb is that any project will benefit from at least 4-5 opportunities to get feedback. So, if a project overall duration is 5 months above then it is worth to consider 4-week iteration. Otherwise, 2-3 WEEKS iteration is a good choice.

• The amount of uncertainty.

When there is a great amount of uncertainty about the work to be done then short iterations will allow to get more frequent feedback and BUILT the correct product.

• The ease of getting feedback.

Choose an iteration to maximize the value of feedback that can be received from inside and outside the organization.

• How long priorities can remain unchanged.

If there are chances of change in priorities then it better to go for short iterations. If we are going with long iterations and there is some change in requirement then we need to wait for 4 weeks to implement them.

• The overhead of iterating.

There is a cost associated with each iteration as each iteration should be fully regression tested. If this is costly, then the team may prefer 4-week duration

• How soon a feeling of URGENCY is established.

As long as the end date of a project is far in the future, we don’t feel pressure and work leisurely. The point is not to put the team under more pressure. Rather, it is to take the total amount of stress they NORMALLY feel and distribute it evenly across a suitable long iteration.