The burden of proof is on the applicant. If all your primary ties are in the U.S., how do you prove what days you were in Canada? Sure, each day you cross the border should be readily documented, but if you are crossing the border two days a week that will not add up to 1095 days in five years, not even close. In fact, four days a week will NOT add up to 1095 days in five years. Not even close.
Add in holidays and some vacation time? Really? That is, assuming you can sufficiently prove all days you were in Canada, and you are in Canada from Friday to Monday every week, for 260 straight weeks, plus another 12 days a year, that just gets you to 1100 days. BUT frankly, when all your primary ties are in the U.S., that is a rather far-fetched scenario. Or, more to the point, it is a scenario regarding which a REASONABLE decision-maker is likely to QUESTION whether all those days were actually spent in Canada, and it does not take a whole lot of doubt to conclude it is possible the applicant was not in Canada for six or more of the days claimed, which would leave even the 4/week plus 12/year claim SHORT, application denied. Considering after all, the applicant's primary residence, immediate family, job, and so on, are all ABROAD (not in Canada), strongly suggesting the REASONABLENESS of INFERRING that any day not for certain proven to have been in Canada, was more likely ABROAD with family or at work.
As
@zardoz observed, the scenario described is at risk (more like very high risk) for full-blown RQ, and it appears all the key information you will need to submit in response to the RQ will document a life being lived in the U.S., not Canada. In which event you could be required to affirmatively prove exactly which days you were physically present in Canada. Little or no benefit of an inference you were in Canada days between a known date of entry and next reported date of exit. (Almost all applicants benefit from the latter inference. Without such an INFERENCE it can be very, very difficult to actually prove presence on a given day.)
To be clear, IRCC or a Citizenship Judge do not have to justify a negative decision beyond specifying why they do not believe the applicant's account.
All this is without mentioning the influence appearing to be
gaming-the-system will have. And this scenario rather obviously shouts
gaming-the-system . . . which, for anyone having difficulty understanding the import of this,
tends to raise a lot of suspicion of fraud. Can IRCC prove fraud? Does NOT matter. (But if it can, and in this scenario any discrepancy in fact is more likely to be deemed deliberate, thus misrepresentation, thus grounds for rather severe consequences.) IRCC does not have to prove fraud; to deny the application IRCC only has to have sufficient doubt about the applicant's case to conclude the applicant has not met the burden of proof. Betting on a sympathetic Citizenship Judge to reach a contrary, favourable conclusion? Good luck with that. A year and a half or more after applying.
Note, after all, a PR living in the U.S. near an easily crossed PoE such as in Niagara Falls, could conceivably just do a daily run for exercise across the border, jogging over the Rainbow Bridge, go through the PoE, circle by the Casino and drop a few coins in the slots, jog back across the Rainbow Bridge. Five times a week adds up to a good regular workout and in five years adds up to over 1200 days presence in Canada. And there is the border crossing every day to actually show presence in Canada all those days.
Technically . . . sure.
Realistically? Practically? The slots are probably a better bet.