Recent anecdotal reporting tends to confirm that actually getting credit for time in Canada as a visitor can be tricky.
As
@zardoz points out, the credit (half day credit for each day PRESENT) depends on the number of days ACTUALLY PHYSICALLY PRESENT, and the applicant has the burden of providing actual presence for all those days. Moreover, the applicant has the burden of showing valid status to be in Canada those days.
BUT it is likely that not all visitors are created equal. Visitors in Canada living with a Canadian spouse, for example, historically have more or less routinely been given the credit for the time they were visiting (again, depending on the number of days ACTUALLY PHYSICALLY PRESENT). In contrast, more casual visitors appear to be at risk, and at least one recent forum participant has reported the application being returned for not showing, on its face, sufficient presence, notwithstanding claiming the time the individual was present pursuant to a multi-entry multi-year visa (it is possible this individual failed to properly populate the presence calculator with information consistent with the requisite status information in the application itself).
Part of the difficulty may be rooted in the difference between other types of temporary status, which ordinarily involve situations where the individual comes to Canada to live for most of the period they are granted such status (work or study visas for example), even though just temporarily, versus the visitor who generally is expected to NOT live in Canada but to in fact be transitory (with, again, some obvious differences depending on the particular situation, such as individuals who have a spouse sponsored PR visa application in process and thus have dual intent while visiting, for whom it is probably easier to prove actual presence).
Reminder: it is strongly advised to have a comfortable margin over the minimum, anyway, and waiting longer to apply can often mean actually getting to the oath sooner, particularly if by waiting longer the case is clearly strong enough on its face to minimize the risk of non-routine processing related to questions about meeting the presence requirement. Many tend to focus on meeting the minimum requirements and underestimate more practical aspects of the process.
