If it is not in the work breakdown structure (WBS), then it is not in the project! This may sound harsh but take these words to heart. Your WBS is where your scope lives. Yes, you have a team member(s) to work with your stakeholders to fully define your project scope. And that scope is documented, and the key stakeholders sign off. Then, you take that scope and discuss what needs to happen to bring that scope to life? What work will be accomplished so that you and your team can celebrate project completion?
The WBS is an easy reference guide for your project. It can be used to educate your stakeholders about how much effort goes into making their dreams come true. And it is a solid basis for planning your resource needs, estimating time, and estimating budget and it helps with risk identification. You can use your WBS to prompt lessons learned discussions and to help plan future similar projects.
Can you do all of these things without a WBS? Yes. In fact, when I was new my team and I did most of these things without a WBS. I say most because there were other things we did not know about – like formal risk management. But, having the project scope documented in one easy-to-view structure? That makes your life so much easier. And do not worry, you will have plenty of challenges on your project journey.