A comment about that "normal memory fallibility" thing: I shake my head when people complain about having difficulty remembering all the places they lived and worked for the last five years. No, it is not normal to forget these things.
I was referring here to a more simple scenario, about entries and exits. I'm asked often enough on entering Canada when I last visited, and my answer might well be "June, I think" when it may have been May. Now I'm also not attempting to fulfil RO, but I expect they are checking my responses against things they can verify (which may be as much about seeing whether I appear to be trying to answer truthfully or body language as the actual fact of whether I visited in May or June). Not suggesting anyone should rely on that - better to know - just an example.
