i think you are not understanding it. its not about how much zoom in/out is on screen. you have to go into the menus and there is a setting for how much details to display on screen and it will show that details regardless of detail level. please go to the Map Detail setting and set it to "Least". your menu may be a little different, but you'll get the idea. Here is where its on a Nuvi 2xx.
Go to Settings>>Map>>Map Detail >> Least