Every official statement I've seen around this is careful to say that they "don't intentionally reduce model quality", which leaves plenty of room for "we adjusted some knobs and our evals show performance is materially the same".

However, I also agree that I haven't seen any robust data from someone tracking it daily/weekly. The handful of sites purporting to do this aren't even running it enough times to hit stat sig.

edit: someone linked one elsewhere in this thread called AI Stupid Level - they "run 7 trials instead of just 1". I don't blame them. Doing this in a statistically sound manner would cost a small fortune.