Kanban as mentioned by this commenter and others are great processes that do maximize productivity, flexibility, and often developer happiness. I love Kanban for the initial cycles of a project and as long as you can keep it going. The weakness of Kanban tends to be in predictability of future delivery, which becomes a problem when external commitments or obligations pile up, or as orgs grow and lot of cross-team dependencies emerge. So you start to lay on more structured agile process so you can better forecast future delivery and protect your team from tendencies to miss-set expectations on scope or deadlines, which can have big impacts on customer relationships or in high level company strategy decisions. So you might consciously start to trade-off in your process design, some efficiency and bureaucracy costs at the team level in favor of making better choices and efficiency at the org level.