Garmin RV 760. We like it a lot but it does on occasion send us silly routes: Cuyutlan to Puerto Vallarta; SOUTH to Tecoman then via Guadalajara. Even putting Melaque in as a way point didn't help! Only when we passed Manzanillo did it sent us straight on, dropping a couple of hours off the ETA.
It also does not seem to know about Columbia Bridge. In November we had just downloaded the map update and it still did not know it. We have done another update but haven't checked Columbia. If it's not there this year we'll try Briansue's trick.
As they said, you have to practice. And never blindly follow. You can send corrections and suggestions to Garmin and they will (eventually) investigate and correct if necessary. They used to direct traffic heading up island from our home to take a route that included two 5 kilometers sections that is signed "Single lane road, Two way traffic". We emailed them the details and within a month or so we received an email from them saying thanks, you're right, it will be corrected in the next update.