It is exciting and fun to blog about innovation and the value in always keeping an open mind in your projects. The smallest idea from the least likely of sources may lead to toward incremental value and innovation or truly substantial change. But somewhere along this path of continuous improvement, you need to find the lines in which to hold your project team. That is where your various management plans and PMP will come into play.
The time spent developing a collaborative PMP with your team will help them come to understand the constraints and goals of the project. Without having to reign in their creativity too often, their buy-in up front will pay dividends from that standpoint. It is also important to encourage them to use the PMP guidelines as a tool just like any other. Without stifling their problem solving capability, you have to keep things within reason. Your PMP will help to guide the team, but like all guides, they are meant to point you in the right direction only yet let the team decide where to take each subsequent step.
At the end of my decision making process, I will typically err on the side of an open mind. Whether your style as PM is to start with strong project controls and definitions and then relax them as needed or to firmly make every decision within the agreed-upon constraints of your PMP, your approach can work well. My style is to innovate along the way using every possible resource. Without a doubt, I have found at times that I would have been better served to have adhered more diligently to the original course. However, more often than not, I have found that a great team can handle change if they want to; that is, if they believe in the innovation or change, and you do to, then make it happen. Period.
Every PM is going to be caused to find the balance between their delivery constraints and goals and their desire to maximize value through innovation. This balance will be unique to every PM and perhaps on every project. There is no right answer, but it is a balance that every PM should be conscious of because managing this balance is a large, unspoken role of a great Project Manager. Good Luck!