Given that I worry about my smartphone battery lasting more than 8-10 hours, I simply cannot imagine counting on it for urgent needs, such as maps. Treated/waterproof maps and decent compasses last a lifetime. My Garmin trail GPS will last so much longer than a phone, especially if used wisely (turn on, use it, then turn off), and I can carry extra batteries, if needed.
To be honest, I see folks watching movies during international plane flights and I wonder why I struggle with my smartphone.
I look forward to the day when electronic devices last weeks, and they can be dropped without worry, but that day is simply not here yet. At least I think it's not.