The example of the first timer running through the Mexican border without stopping for the required papers processing is not an example of blundering.
It is an example of ignorance and not being ready to ask questions , or expecting the Mexican border guards to babysit you through the process. The Mexican border does not work on the same policed control model as does the US border or the Canadian

If one is going to cross the border into Mexico it would seem logical to determine beforehand what the official documentation requirements are .
Once one knows what is needed it is only a question of getting your passport ,ownership and drivers license in order and going through the steps at the border to do those things .Not doing them is not a option .

The location of the service points can be worked out when you get to the border at whatever place you choose to cross , as long as it is an OFFICIAL point of entry .
As they say , ignorance is no excuse .


As to the question of whether an insurance will refund for unused days it may depend on what kind of insurance or the particular company's policy .
I used to buy trip insurance from Sanborns and never heard anything about such refunds so it was made a point to not buy excessive coverage time . The last decade I have been buying drivers license type of liability insurance each time for a full year . Obviously that does never come to a refund but the overall year cost is less than buying several individual trip policies .
It is a question of doing the arithmetic . If the number of days in Mexico is more than around 34 or thereabouts an annual DL -type policy is a far better deal for me . Also having a year long policy frees one from the need to hasten back out of Mexico by a deadline date ,much more relaxing .Having such a year-long DL policy then pemits me to make several trips in Mexico using a different bike or a car if I wish , and each time I will not need to spend time and money arranging a new ,short trip insurance policy .

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http://advrider.com/index.php?thread....207964/page-5 then scroll down to post #93