Firstly, nobody really knows as the procedures are not spelt out anywhere. A lot of the info seems anecdotal.
Entry-exit doesnt take 1-2 years, but yours is not the only application that they need to check. They do it 'for the most part' in the order that its sent for secondary review, complexity of the case etc. They dont have exit tracking here so they will need to investigate your passport and your CRA records and your Provincial records etc depending on the access they have for the time you are saying that you spent here. For that, they will need to send record requests to the various agencies. And then, match it up with your application. In the meantime, they might be working on some other case before they come back to yours. This is not an excuse, but merely stating what a normal job would entail. And then, in some cases, I do believe they want to see if the person actually intends to stay here beyond the 2 years. So its hard to tell. They are given significant latitude. If you need to urgently travel, they have given only 3 options and your case will be brought forward for sure. If you are already abroad, the only choice is a PRTD. I know its not the best answer but its the way they are functioning right now.