I can not respond about YYC, as I do not fly trans-border from there very often (maybe once in the last 10 years or so).

But YOW, which has a smaller airport - your are giving yourself no leeway if something happens - you are taking no account of contingencies - ie unexpected delays (even with nexus/GE) - I would personally give yourself one hour if you have no checked luggage. Of course, with checked luggage, the minimal required check-in time is indeed one hour before flight departure.