Non-zero purge age for Calendar Hierarchy

I have a a purge-age question, specifically about the calendar hierarchy.

Currently, the calendar in my domain contains weeks for FY2017 through FY2021.

I loaded a new calendar that contains weeks for FY2018 through FY2022 (No weeks for FY2017).

After I load this calendar (with no purgeAge override, default in config is 366), I was expecting to see the weeks for 2017 get a "date" in the info:status for hmaint.dim_week.All weeks have an "NA"

Questions

1. Does calendar behave differently, regarding updating and managing purge ages?

2.I see the same behavior for v16.0.3.21 and 14.0.1.0.901

3. Has anyone successfully used a nonzero purge age when loading a calendar hierarchy? Our current production (and most of my implementations) - calendar is always loaded with a purge age of 0 (over-ridden when loadHier is executed)