I hate these articles that tell you that you have to have every idea planned out to its completion before you start a project, but by the same token, I hate the articles that tell you to just wing it.
I have a project management background, so I fall firmly into the planning is a part of your success category, but I also don’t believe in over planning because I feel like that is a formula for creating an ossified and stagnant project environment.
Here is the thing, planning is part of the project lifecycle. And, you need to plan just enough so that you are comfortable with the ambiguity that is inherent in all projects…so plan, plan, plan, but never so much that you can’t adjust to the facts on the ground.