In October 2020 the United States Coast Guard issued a Marine Safety Information Bulletin regarding how to perform a check of a VHF Marine Band radio. The use of Channel 16 for performing a radio check is explicitly discouraged in the Marine Safety Information Bulletin. See
https://www.dco.uscg.mil/Portals/9/DCO%20Documents/5p/MSIB/2020/MSIB-20-20.pdf