Agencies often have a studio method for how they work through projects. I've witnessed a variety of approaches and consulted with Clients and Creative Directors about their own internal creative processes.
There is not a single silver bullet magic formula to generate great creative and have consistent eureka moments. Instead, there are many formulas. What's important to recognize is that every agency just like every individual may have a method they already know that works best for them, but that method may not work for everyone else (client or team member).
Within a creative agency it’s up to the team members to propose new ideas on how to work through a particular project, and present the correct checks along the way to ensure great creative has the room to germinate but not run off the rails.
I’ve witnessed countless designers approach their own work in ways that may differ from my own and I respect that. I always encourage them to bring their process to the table and share it with everyone else so we can all learn. Every person thinks differently and we need to appreciate that that while my method works for me, it may not work for my peers, but I should feel comfortable sharing my approach with all to decide.
The right approach should be chosen that works best for you and chosen just as a tool is chosen for a specific task. Once we document and recognize unique methods, we will be empowered to grow and arrive at new ideas. If there is anything that's broken in the creative process it's that we are working in environments that too stuck in their own methods and do not encourage occasional failure and experimentation.