It is possible, but not recommended to skip versions. If you trade Z systems, you should definitely update or you risk an expiration of old systems. If you don't use Z systems, you should also update, for stability reasons. Any update of any software contains bug fixes as well as new bugs. But the new bugs normally only affect the new features, while the fixes affect bugs in old features of the version you're already using. So you're always better off with an update.