Sara and I use a TomTom device when we travel and it has helped us a great deal. We found however that many churches are either missing or incorrectly located. You can help by checking to see if your home church or any other church is accurately listed on your GPS.
Sometimes street addresses are incorrectly located and you may end up a good distance off from where the church property actually is. An option is to locate a church as a “place of worship” within a city - which hopefully will take you to the actual coordinates.
Depending on the device you use, you may be able to correct or add a named location simply by being at the particular place and using "map corrections" for editing or adding the point. On TomTom devices a church should be listed as a "place of worship" in your "points of interest". Sometimes a previous listing contains just part of a church's name, not telling what type or denomination the church is. You can fix that simply by creating a new entry with the church's full name.
If you use a TomTom like we have (I don't know about Garmin), you can share your map correction changes with everyone on the TomTom network when you connect to update your device by computer. I would recommend sharing any corrections as soon as possible so that there aren't several users with the same correction to upload.
Fellow missionaries, if possible please help make these corrections. It will not only benefit all of us as we travel from church to church, but will help everyone else be able to find the churches too.
Warning: Never depend on your GPS to be 100% accurate. It is good to double check your route using MapQuest or Google Maps.