I have a question about all this

so long story short I’m thinking if they’re super deny happy for visitor visas for ridiculous reasons that I don’t have the funds to keep retrying to apply for a visa if theyre denying people for bs reasons.

I have a valid ETA and since it’s valid for 5 years and my 6 month stay is almost up, I’d like to extend my stay but reading all these refusals and their reasonings I’m getting anxious on applying. If I were for example to fly to the US and stay for a few days could I then fly back to Canada on the ETA and have it “reset” the 6 month stay timer? would this be a for sure guarantee that I could come back?