AI-assisted development is causing a new form of burnout called 'single-mode burnout' by collapsing the three natural cognitive modes of software development: Planning, Implementation, and Integration. Implementation — the flow-state mode that provided cognitive reset, tangible wins, and skill-building — has been largely automated away. Planning has intensified as organizations expect more output, while Integration has been stripped of its reflective and relational qualities, becoming a pure audit of code the developer didn't write. The result is developers spending most of their time in the most demanding cognitive modes with little recovery. Long-term concerns include skill atrophy (since building is how developers grow), motivation decline, and reduced code quality due to weaker mental models. The author advocates for intentionally protecting implementation time and redesigning team workflows to restore cognitive balance.