TN Visa at Consulate or POE?

Since it was changed so that Canadians don't need to go to a POE to apply for a TN (I can't include the link because I'm new ), is it advantageous to apply for a TN before I go to a POE?

To me, it seems like it would be because you can go a POE without the worry that you will be denied. Also, at a consulate you can be denied without having a border denial be on your CBP records, does that sound accurate?

Okay. Would mailing it in be advantageous though?

Even if you were able to fix it within the same day, would you not still miss your flight?