I Noticed That My Gps (garmin), Is Not 100% Accurate As To When I Get To The Input Address, Is That Common?

Yes.
Addresses are often times calculated by block on these types of systems- especially in GPS systems, which have street addresses overlaying the actual coordinates.
Here’s a good way to see this in action- go to Google Maps and look up your address, or an address that you are familiar with. You will notice that the point that shows up is pretty close to where you know it to be, but it is often times off (for instance, my house is in my neighbor’s yard).