We're on 12's almost exclusively in Ontario and definitely at my service (3rd service, municipal ALS, limited FD response. 1.1M served, 80K calls per year). I work at one of our busiest stations and have for 7 years. We have 2x 24 units plus our deployment moves us to stations (sometimes far from home) to cover off other stations. I run 5-6 per 12 plus redeployments. I like being busy and will try to stay in a busy station when I come back to Ops after school.
That being said, these numbers being thrown around are not safe for the provider, the patient or the public unless they have some strong rest period policies. Non-stop for 24-48 for work is killing us as providers and probably killing patients.
I'm fortunate to not get held over for OT very often these days (some novel policies to decrease this) but regardless I'm an legally not allowed to work longer than 16hrs without being provided sleep facilities and sleep time. Since we do 12's the translates to OOS drive back to base and have next shift start delayed with pay to ensure adequate rest before reporting in.