The general rule is if it works don't upgrade. Some firmware is intended for incorporating new products into systems, maybe another updates to grid codes, others may address an issue or add new features. There is a changelog in the professional area which should give you a good idea of the types of changes and whether it is actually necessary for you to upgrade. I'd suspect there would be reactive updates for issues and roadmap based ones, but this is only my view.
There are no timelines for firmware releases. Updates usually add features and these are released every few months on average. Updates which fix problems are released in shorter times.
30 People are following this question.