Codex attempts to one shot for me but there’s many rounds of refinement. I haven’t used it in the last couple of weeks because it’s disappointing. Over hyped. Gone back to Amp and a little bit of Cursor with Sonnet 4.5
This is my entire problem with Codex - it will spend ten minutes trying to one shot a problem and usually go off the rails at some point, whereas Claude seems much better at incrementally finding the right solution with me.
I've heard this from many people, but I really haven't had this experience. Sonnet will write code that doesn't work, but Codex will give me working code basically every time. It does take longer, and it does think a lot, but I've never seen it go off the rails.
I do look at the backend code it writes, and it seems moderately sane. Sometimes it overcomplicates things, which makes me think that there are a few dragons in the frontend (I haven't looked), but by and large it's been ok.
If I'm doing a large task, I use GPT 5 Pro to write a spec first (with advice for Codex, broken down task list, snippets etc). I may also supply entire files/repos as context for 5 Pro to produce this.
If I skip 5 Pro but still have a large task, I have Codex write a spec file to use as a task list and to review for completeness as it works.
This is how you can use Codex without a plan mode.
Well, when you use GPT 5 Pro Mode it can't make any code changes, so not really a problem :)
I have similar workflow as parent, GPT 5 Pro for aiding with specifications and deep troubleshooting, rely on Codex to ground it in my actual code and project, and to execute the changes.
Codex won't read as much of your code as 5 Pro will (if you give it the context), and Codex will skip over reading in context that you give it (5 Pro can decide what's relevant after reading it all).
Yes Codex is still very early. We use it because it's the best model. The client experience will only get better from here. I noticed they onboarded a bunch of devs to the Codex project in GitHub around the time of 5's release.
> and Codex will skip over reading in context that you give it
That hasn't been my experience at all, neither first with the Codex UI since it was available to Pro users, nor since the CLI was available and I first started using that. GPT 5 Pro will (can, to be precise) only read what you give it, Codex goes out searching for what it needs, almost always.