I reckon you've not had any replies to this because the question is a bit ambiguous. However, I'm guessing you're not interested in the finer points of what goes on behind the scenes in the device.
I don't have a 220, but am familiar with recent Garmin products. From a user perspective, there are a few settings on the device to let you set shortest/fastest routes and things to avoid like toll roads or motorways. You also have the option to set different profiles so you can have different selections of these settings depending on whether you are on the bike or in the car etc. After that the simplest way to use the device is just to select your destination and dumbly follow the instructions. BORING..................
Then again, you can be in charge - and this is how I use mine.......
Set the satnav to never recalculate routes. Plan the route using Garmin's Mapsource software on a pc. Settings on the pc to not avoid anything. Set the start and finish points and let the software plan the route. Then modify the route so it travels on the roads you want to be on. Drill down and check very carefully that its exactly as required (the software is rather sensitive to where you drag the route). Then upload onto the device and follow your own route. Lovely.
Hope that helps.......
Iggy