interesting discussion :-) I think Syed hit the nail on the head with startups... GDD is perfect for startups for many reasons (quick launch, ability to iterate as the business iterates, flexible, etc). However, it's equally as important for scale-ups and mature businesses as well.
In terms of workflow, did you have a specific challenge you were running into? If you're running SCRUM and sprints, GDD is perfect. If not, it can still work, but will be less efficient. Please let me know