> It looks like full time work would require the 20x plan.

Full time work where you have the LLM do all the code has always required the larger plans.

The $20/month plans are for occasional use as an assistant. If you want to do all of your work through the LLM you have to pay for the higher tiers.

The Codex $20/month plan has higher limits, but in my experience the lower quality output leaves me rewriting more of it anyway so it's not a net win.