I would love to know enough about my projects to predict them perfectly. But, I rarely do. That's why I use rolling wave planning, no matter what life cycle I use.
In a serial life cycle (waterfall or phase gate), you can lay out all the major milestones if you know what they are. But you don't plan in detail how you get to each milestone. Instead, you plan for the next 4 weeks--no more than 4 weeks--in detail. The way I do this is:
- Get everyone on the project in the same room
- Decide on a milestone (not necessarily a major milestone, just a milestone) that's a month away
- hand everyone a thick black marker and a pad of yellow stickies. (I need people to use the 4"x6" stickies because I can't read what they write on the smaller stickies. If you have people with younger eyes, use whatever size stickies you want :-)
- I ask this question "What will it take you to achieve this milestone?"
Then I get out of the way. I let people write their tasks down and argue about who has to do what. I make sure no one starts a physical fight. If we have questions, I keep a parking lot of stickies on one side. I ask people to put their stickies in time order, left to right with the earlier tasks on the left and the later tasks on the right. If there are dependencies, note that with sticky placement.
I request that people create small tasks, inch-pebbles (one- or two-day tasks that are either done or not done). If people have week-long tasks, I work with them individually to break the tasks down into smaller pieces.
What you have now is an on-the-wall-sticky Gantt chart. But you only have 4 weeks worth. Now you have a couple of choices of how to proceed:
- You can either ask everyone to get together to do this planning for one more week every week, or
- You can ask people to plan their own tasks weekly and once you've achieved a major milestone, now you get everyone back together.
The key is that you always have a month's worth of detailed planning. You never have more. You never have less. If you laid out the major milestones, everyone knows what they're trying to achieve as a group. If you're managing the project, you have much more insight as to how well the plan is going vs. the actuals.
With an iterative life cycle, such as the spiral life cycle or RUP, or with an incremental life cycle such as staged delivery or EVO, this is even easier, because these life cycles deliver prototypes or finished code into the code base earlier.
With an agile life cycle, I use rolling wave planning not for the schedule, but to better my prediction about which features might be delivered in which iterations (assuming the product owner doesn't change his/her mind much about the ranking of features).
No matter what life cycle you choose, consider adding rolling wave planning to your toolbox. Especially if you can't predict much. You don't have to, and you gain tremendous benefit by seeing the details for the next few pieces of work.
