We work for this client from more than a year using agile methodologies. We did firstly performance optimization to support high spike traffic, then the client shared with us a roadmap for all the implementation required to support the business. We're still working on a weekly schedule for continuous improvement.
One of the first Magento 2 implementation, started with a 2.0 and then upgraded to 2.1 during development. Also in this case we did a complete implementation: custom frontend development, custom system integration with client's ERP, AWS cloud hosting.