No. of Days present

Technically the burden of proof to show compliance with residency requirements is on the PR; the PR tells the truth to CBSA or CIC, and they then "know."

That does not mean, however, they necessarily take your word for it.

Really does not come into play unless for some reason there is an issue, and then what matters is the context, the collateral circumstances, the how and why and nature of the issue.

In the meantime there are a wide range of indicators of presence or absence, ranging from work and address history (which ranges from easily verifiable to rather questionable), health card use, other indications of presence like bills, leases, property ownership, transactional history, all of which, of course, can lean one way or the other (transactions out of the country tend to show absences). What access CBSA or CIC has to sources of information related to this without asking the PR to produce it, I am not sure. Theories range from minimal access, or at least minimal use, to whatever the imagination can conceive a government agency mining for data -- criminal and credit report like histories seem likely, beyond that many of us have speculated widely. We do not really know.

But, again, usually takes an issue to even make this a real question, like being abroad without a currently valid PR card and applying for a Travel Document in order to return to Canada -- then the questions arise, and then, again, the burden of proof is on the PR to show compliance with the residency obligation.