Some advise to those of you that try to load all 20 maps on a GPS (Etrex, Oregon, 60/62 etc.):

There is a limit to the amount of maps (different FID's) that can be used, on my 62s the limit is 16 maps (basemap included) and that's for internal memory + SD card. So you can only load 15 of these maps, the 16th map won't be dispalyed in the map-setup menu and is not loaded. If you really need all 20 maps just use 2 SD cards.