Some people mock planning saying that planning just takes time and doesn’t add value, but creates a plan, a guess, up front which you then need to stick to. I disagree, at least in part.
Planning is very valuable. Ask any senior manager in any company and they will say that there is a lack of people who can plan their work and communicate it clearly, weather to colleagues or customers. However, the value is not in the end result, in the document that is the plan. Rather, the planning process itself is where the value is.
By planning, you get to think through what you want to do and how you are going to get there. Through thinking, you realize any eventual problems and can evaluate weather you need to address them right away, take a different route around them, or just keep them in the back of your mind. When (or if) you hit them, you will at least be aware of them and can act better and faster.
Even though you might not necessarily always keep to the plan, the process makes up for it. As long as you then clearly communicate with other stakeholders in your project what is happening, you may deviate from the plan if it makes more sense. Communication and planning goes hand in hand and makes for happier coworkers and customers.
In conclusion, in every time of scenario where any type of planning is involved, it is the process that creates the real value for you, where you get to think through the project or the task ahead of time. Every hour of planning as they say, are returned several-fold over the course of any project.