I still grab free AAA maps before road trips, lol. Marking rest stops and gas stations with a highlighter helps if you lose service. Always keep the map in a ziplock bag too, because snow and coffee spills happen. That combo's saved me a couple times when my battery dipped below freezing.
Seriously, paper maps are the best... I never go without one. Got caught in a snowstorm last winter and my phone was useless. The old map in my glove box had a back road that saved me hours. It even led past this crazy beautiful frozen waterfall I would have missed. Those little surprises are why I still rely on paper.