I easily spend 3-4+ hours a day looking on Google Earth for back country zones. It's an amazingly useful tool.
This past weekend I toured both days in the NEK on logging roads and clearings I found from GE.
I will say that some times the sat data isn't always up to date AND what the 3D and topo lines show isn't always as detailed as it could be. I often find deep gullies and creeks beds which don't show up when browsing GE. Little surprises which make the tour challenging. I hit a creek on Saturday which wasn't frozen over, was deep and rushing. Couldn't cross. Had to re-route myself into a different zone.
Still though...I'm addicted.