Interesting, how does TomTom save you time over the gmaps navigation? I just tell my phone, "navigate to <business name>" and 15 seconds later it's telling me where to go. What am I missing?
I don't have a data plan on my phone, so I use offline mode whenever I want to go somewhere. It's pretty great, I just need to remember to save the route before I leave WiFi.
The only limit to how big an area you can cover with Google offline maps is your storage. Each individual offline map is limited in size but you can download as many as you want to cover as big an area as you can fit in your phone.
> Note: Downloading offline areas isn't available in some regions because of contractual limitations, language support, address formats, or other reasons.
100+ 120,000 sq km areas, huh? You visit 12 million sq km of land on a regular basis?
Yes, Google can't provide offline maps in some countries. This is true of all mapping applications, though some have better offline coverage than others, nobody has everywhere. For example HERE does not offer offline maps in Japan or South Korea.
You'll need 100s of areas if you want to minimise your local storage usage, and micro-managing that would be a PITA. GM announces 'up to 1750mb' to download the part of my country I traveled to in the last month, it's a non-starter.
Compare that to the 179mb/113mb that I need with OSMAnd/Maps.me for the whole country without fiddling. Add to that the fact that OSM's data is significantly better than Google Map's for my country (YMMV) and that there's no such thing as "offline mode not available in some regions" with OSM.