Yes, MarginLab only tests 50 tasks a day, which is too few to give a narrower confidence interval. On the other hand, this really calls into question claims of performance degradation that are based on less intensive use than that. Variance is just so high that long streaks of bad luck are to be expected and plausibly the main source of such complaints. Similarly, it's unlikely you can measure a significant performance difference between models like GPT 5.4-xhigh and GPT 5.2 unless you have a task where one of them almost always fails or one almost always succeeds (thus guaranteeing low variance), or you make a lot of calls (i.e. probably through the API and not in interactive mode.)