All plans are educated guesses, and in truth the futher into the future we try and gaze the higher the likelihood that our plans are really just guesses. We often use an analogy to cyclone or hurricane forecasts when we are explaining this.
Meteorologists can forecast that a big tropical storm (please insert hurricane or cyclone in your mind depending on whether you’re reading this from the top or bottom of the world) is coming 4 or 5 days out, but it’s not clear at that point where it’s going to land. Instead they predict a wide potential path. As the storm moves closer and closer to landfall the accuracy of the storm’s path increases until about 8 hours out when we know within some 10s of km where the storm is going to end up.
Planning for large projects is just like this; we can have a good idea of the major direction of travel but working out the fine details of what is going to happen in a few months is unrealistic. This is one of the key reasons that so many Waterfall projects run into trouble; to continue the analogy, the wind changes direction, customers’ demands and desires change, the regulatory environment changes or perhaps a competitor enters the market etc.
So this is not to say you shouldn’t plan; you need to plan. Just understand how far away the storm is. If you’re thinking about next week, it’s valuable to plan in detail (stories, tasks, detailed estimates and wireframes etc). If you’re worried about next month, break it down into the major tasks, but don’t get too worried about the details yet. When you’re looking at what you’ll be doing in 3 months, remind yourself that this is just your best guess is; know that it will change.
Having these longer term plans is still very valuable, but often not for obvious reasons. Having a plan gives you something to push, pull and test alternatives against. We humans are very very good at comparative value calculations and very bad at abstract ones. So the plan in place gives you a benchmark against which to decide whether a change will be an improvement or not. It also gives your team a framework around which to make bigger decisions about platforms, architecture and longer term expenditure – again just tell your teams and yourself:
“This plan is just our best guess right now, and we promise to keep talking about it and keep updating where the storm is going to land as we go.”