it is more economical to carry a laptop with charting software, electronic charts and a USB GPS receiver that to carry paper charts. Especially for world cruisers. I used to carry hundreds of charts that were bulky and heavy. Is there a possibility of two systems failing? Sure. I also plot and record all waypoints needed before a trip so that a simple handheld GPS could get us in.

BTW. In reference to the Rule 62 tragedy, I have, many a time, sailed away from an unfamiliar port to wait for a daylight entry.