Agile : Scrum : Why Time boxing Why not milestone driven schedules …

A big mind set change for a lot of teams moving from waterfall or iterative methods to agile is a strict adherence to time boxing of schedules.

Issues with milestone driven waterfall schedules :

1. Using different sized milestones causes teams to have variant levels of intensity
• A long duration mile stone will see low intensity during initial days, and very high intensity closer to the milestone deadline.
• The team does not get used to any rhythm and will need some one to keep reminding the deadlines and schedules with many internal milestones.
• Because the team does not break down features into smaller chunks the uncertainty of estimates in longer milestones is larger, causing bigger delays and late visibility in to the delays causing larger surprises.
2. There is no motivation for mind set changes that teams need to make to get more agile and collaborating as a cross functional team. They can still define large milestones to keep doing the waterfalls in larger milestones and can work the milestone lengths to fit the waterfall.

Advantages of Time boxing :

1. The idea of time boxing ensures that there is a steady rhythm that the team gets used to.
2. Having time boxes and sticking to them ensures we can review our process and how we worked to achieve the time box goal quickly after the time box ends.
3. Time boxing (esp with small iterations) need the team to change the way they work and typically force mind set changes.(NOTE: Longer iterations can still be water falled by the team, so time boxes and short ones at that are better).