How do some of the churches calculate employee senority for their mus

[Guest KennyG53]

I have been a church musician since 1968 in the Archdiocese of Detroit.

I haven't been playing for the same church all this time. There has been some off months, but I have performed during almost all the years since I started. Was it my responsibility to keep track of my senority? Is there such a benefit status for part-time employees?