Sure we have to wait for non urgent matters, but my step-mom died of cancer nearly 2 years ago, so I can attest of the efficiency of the system in her case. Each time she felt bad enough to go to the hospital, she was taken care of in matters of minutes in the emergency. Any necessary scans were done quite quickly.
Getting a diagnostic was a bit tough though, she had to get multiple appointment before they found the cancer, but I think that's mostly because cancer can be hard to diagnose. Once they found it, it was too late and what was initially potentially treatable lung cancer, became 4th stage and reached her bone.
The day she was asked between fighting or not a lost cause is the day I understood how our system is so much superior to the US one. The government bought us 4 or 5 more months with her. There 4-5 months that would have cost so much, 4-5 months that she wouldn't have agreed to if they had to pay.
Once I forgot to renew my insurance card. I was still insured, but I just couldn't benefit from it directly, which made me postpone it later and later, until it was needed after hitting my knee quite bad. That day I also was thankful for our system, because I hesitated to go... it was the first time I experienced what so many people have constantly experience in the US. If I still had that card, I would have never ever thought of any of that, I would just go. That was for a situation where I would have been able to get it refunded too, imagine that. Finally it was only about 80$ to get a scan of my knee, the people at the reception didn't even know how to charge me, that was funny. The funniest is that you would probably save money by getting that scan here in Canada, I have no doubt that it would be much more than 80$ in the US and you would still have to pay your full 100$ copay.