Your solution is a good one too. But if ProSeries does not change the file name (or if you do not change it) and you print a 2021 organizer, the file name is "2020 Smith John.21o" unless you change it.  This can be confusing to clients, because they might think you are sending them last year's organizer.  They would have no reason to pay attention to the .21o extension... unless you tell them to.