According to zxcvbob :

A subpanel *in a separate building* is treated like a service entrance.
Service entrances must have 6 or fewer switches to totally disconnect the
power to the building. If your subpanel is in the same building as the
service panel, this (NEC) rule doesn't apply. I don't know about the CEC.

I believe there's something similar, but less than 6, and/or it doesn't apply
to pure residential.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.