The 10-30 minute coding-agent loop is the danger zone.
1-2 minute loops are basically acceleration: you stay in the code, use the agent to type, test, and explain faster.
Multi-hour or all-day loops are real delegation: the agent owns a bounded task, you check the artifact and trace later.
The painful middle asks you to be planner, reviewer, debugger, and context cache across multiple half-finished branches.
That creates a very specific tax:
waiting becomes parallelism
parallelism becomes context switching
context switching becomes shallow review
shallow review turns into distrust
This is why agent workflow design matters more than raw autonomy demos.
A useful setup has to choose a control mode per task:
fast pair-programming
slow delegated job
or explicit manager layer with specs, small PRs, traces, and reset points
The worst state is partial technical control with no memory system. You still own the code, but the context lives in scattered agent runs.