the version number goes up about every year, but updates are posted throughout the year when needed to fix bugs and betas of the next version are put out to test new features.
Once a version is in beta (like v17 is now) it probably has it's new features decided on and set. Any new features proposed and implemented would wait for the next version.
After the beta period , the version is "released" and there may be a few updates to it after that to fix new-found bugs, but most of the programmer's activity will be on whatever the next version is gong to be.
Thank you for the info.