its essentially the same model being trained continuously 24/7 with the company periodically publishing just a new checkpoint

each new checkpoint can benefit from better reasoning training, RL on specific tasks and more synthetic data

So why do they seem to release around the same time ? my guess is because they time major releases around quarterly earnings, investor meetings and other important business milestones. Once one company announces a major update, the others also have an incentive to ship their latest checkpoint rather than look like they r falling behind.