I fire it up when I leave the dock, and turn it off when I return to the dock. I have the Lowrance HDS7, which draws very little power, it's also my depth finder, and in a few months, it will also be my radar screen as well. It's my anchor alarm, speedometer, plotter, and soon will also be connected to the engine instrumentation. I've had GPS/ploters since they first became available, always used Lowrance, and never had a failure. I think the technology has advanced so much in the past decade that if it works right out of the box, the only way you'll be able to kill the machine is with a shotgun.
I still have a chart table filled with paper charts and book shelf with loads of chart books. They have not been used in more than a decade. Maybe one day they'll become valuable antiques and I can sell them for big bucks.