It seems that in the backcountry of Canadian parks, one may only camp on campgrounds, and reservations are required. For example, in Jasper National Park, one must camp on campgrounds to be reserved in advance, and from the Algonquin Provincial Park regulations, point 6 states that you must not camp at other lakes (...) not specified in your permit (emphasis theirs). Even the very remote Tombstone Territorial Park requires early reservations. It amazes me that this is the case in a country as vast as Canada, but it seems this rule is universal in (popular) Canadian parks.
I understand the rationale behind the rules, but I don't understand how it can possibly work. Maybe I can somewhat plan where I sleep on a one-night 40 km trip in Algonquin, but if I'm going to hike for 200 km in Jasper National Park, I don't see how it's possible to know where I will sleep 12 days in advance, as this strongly depends on weather and trail conditions, that vary day to day. If the weather is very bad for a day I might be a day behind, and I would be violating this rule every single day.
What are the consequences of doing so? Of course, campgrounds may be full, and those who are there on the specified day are going to be annoyed. But it will surely work out in practice (perhaps by illegally camping outside the campground). The question is: how do rangers handle the situation? Are they flexible in enforcing the rules, or may I end up with high fines and be blacklisted for any more backpacking permits in Canada?
(Perhaps the easiest solution is to avoid parks on backpacking trips, but that means avoiding the most scenic areas that have developed trails!)