You mean codex (client) with GPT 5.4 xhigh? I am using Codex 5.3 (model) through Cursor, waiting for Codex 5.4 model as I had great experience so far with 5.3.
Yes and no. It's bad because of shorter context but it does have auto-compaction which was much better than Claude. If you provide it documentation to work from and re-reference, it works long-running.
Honestly - 'every inch of IQ delta' seems to be worth it over anything else.
I'm a long time Claude Code supporter - and I'm ashamed to admit how instantly I dropped it when discovering how much better 5.4 is.
I don't trust Claude anymore for anything that requires heavy thinking - Codex always finds flaws in the logic.
I tried to use 5.4 for something pretty straightforward - create scripts to automate navigating a game UI and capturing the network traffic. 5.4 was super frustrating, constantly stopping and waiting for feedback etc, even after telling it to never wait and just iterate/debug. I quit and switched to Opus 4.6 and it did much more of the work by itself.
I've never run into that problem, but these were coding solutions in codex with a strong plan, steps to work towards.
It could be that if you're using massive tokens on a 'plan' then then want to limit u in a way, or even if the objective is not perfectly clear they don't want semi-random token use.
See if the token/sub solution behaves differently. Make sure that when it 'compacts' that it re-reads your instructions clearly.
