Is requesting a mortgage payoff quote necessary if you're on automatic payments?

It is necessary to request a payoff quote for a mortgage, get it in writing, go through all those extra steps… Or is it also possible to simply pay down the mortgage with an extra principal payment to something like $100 and let the next automatic payment take care of everything automatically? It would seem easier to let the system make the final payment, but I'm not sure if it's the best, am I missing something?

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