It's when you have to iterate to handle changing business needs, scale issues, and integrate with other systems where the entropy becomes a scary concern over a long enough timeline.
And it's not just "checking" - it's wholesale rejections of code, reframing prompts to target specific classes or approaches, etc... I don't think you will take the human out planning any time soon.
Honestly, I believe lower court judges will be the first job in the legal industry to become fully automated.