I can see why too - the instructions you get from navionics, and what's available on the web, really don't show all that you need to know and do to use the program and your sonar to it's fullest potential with the program and sonar that I have. I was surprised myself to see that some areas that I know are heavily fished by serious guys doesn't have more information in their maps, but I think many guys don't take the time to record their loss and update their maps for the community. Then the next time you go out you will have all accurate information. Basically, those maps will get you started, but then you need to record and upload your specific sonar logs.
I have navionics+ and also update to the community function every trip.
