How frequently can a visitor visit Canada?

[hobbes]

My Mom has a multiple entry visitor's visa to Canada. She visited us last year from June-November. She would like to visit us again this year from March to September. I am thinking if CBSA would consider that as too frequent?

Is there a thumb rule on how often can a visitor enter Canada?

 

[Jalex23]

My Mom has a multiple entry visitor's visa to Canada. She visited us last year from June-November. She would like to visit us again this year from March to September. I am thinking if CBSA would consider that as too frequent?

That's fine.

Is there a thumb rule on how often can a visitor enter Canada?

No.

A good way to tell: if she has been more than 6 months of the last 12 in Canada she will most likely have trouble in the border.