CBSA also considers things like the age of a visitor when reentering Canada after already spent a significant time in Canada. Unless independently wealthy most younger people need to work so it would be unusual for a younger person to be able to visit for a long period of time during a year and multiple times in one year. There will be suspicion that a visitor may be working illegally. The visitor may also be required to prove that they have sufficient funds to support all this travel without working. If the visitor is older or retired it is more reasonable that they are able to spend a longer amount of time in a year being abroad.
