I've used ON for years. While it is a bit quirky and cumbersome, and is NOT a quilting product, I still like it and don't plan to change.
Be aware that when you have an attached GPS
and are in the "Follow Vessel" mode, the program will bring up new charts along the path automatically.
But, when in the planning mode, you have to do it by hand.
I find that if you put the curser off the chart in the desired direction, then right click, one option is "Charts at the Curser", and it will list all charts in the library which cover that point (where the cursor is). You can then select the one you want.