Anecdotal, but putting in $10 and using it through codex, I blew through it in maybe 30 min to an hour of a light test drive and didn't get my little task done, which certainly didn't seem like any sort of token burning operation. I honestly wouldn't mind trying it more, but it didn't impress me enough to put more into it.
I also put $10 into DeepSeek when v4 came out and (checks) still have $6.30 in there and have gotten so much more use out of it.