Should You Put All The @id Info On A Subdomain If You Have A WordPress Site Instead Of A GMB Mini Site?

In episode 218 of our weekly Hump Day Hangouts, one viewer asked if one should put all the @id info on a subdomain if you have a WordPress site instead of a GMB mini site.
The exact question was:
Hello hello. Had a question about the @id. If we have a WordPress site opposed to just the GMB mini site, would we put all the @id info on a subdomain. One thing I noticed in the Google documentation for Local Business Schema is this sentence:
If the business has multiple locations, make sure the @id is unique for each location.
So is it a good idea to structure it like:
city1.domain.com
city2.domain.comIf there is more than 1 location. And possibly city.domain.com if it's just 1 location?
