The rule Changed on Jun 18, 2018. Now the subsequent visits are for 2 yrs unless otherwise date mentioned on the stamp.
But dn't just exit and try to enter on super vis to just extend the stay, its red flagged in the system.
File for an extension and you can get for 1 year on super visa.
SUPER VISA UPDATE
Program delivery update: Super visa guidance – June 18, 2018
This section contains policy, procedures and guidance used by Immigration, Refugees and Citizenship Canada staff. It is posted on the Department’s website as a courtesy to stakeholders.
The guidance for super visa holders has been updated to reflect that each entry to Canada should be for a duration of up to 2 years and extensions should be for 1 year. Specific instructions for border services officers and processing offices in Canada have been updated.
But that's what I find absurd. They haven't stated a minimum exit duration. I was thinking of trying our luck by just going to the US for a week, instead of the home country. Is that also frowned upon?