https://tinyurl.com/MyFDresults
A vigorous five-mile walk will do more good for an unhappy but otherwise healthy adult than all the medicine and psychology in the world. ~Paul Dudley White
I guess paper could fail if it got wet, but it's more reliable than an electronic device. Some of the newer electronic offerings are really neat, so I may supplement, but I don't think I'd hike without something on paper, at least a map.
As a section hiker (we never hiked more than 170 miles on one trip), it gave me the time to prepare for - and then savor - each trip. I took information from various places and consolidated it into a single document that was formatted to print on quarter pages. Fold it twice, and it had each planned day's information. I still do that now for hikes elsewhere, looking at Trailjournals for recent experiences, or those in a similar season. And I carry a map.
I hiked a 600 mile section of the AT with just AWOL's guide back in 2012. There were no smart phone apps when I thru-hiked the PCT though I had paper maps. So Far Out and other phone based apps are really an optional thing. Plenty of people successfully hiked before them.
That said, the gps based phone apps are convenient with one advantage of knowing exactly where you are at a given moment. There are a handful of times that I make a wrong turn when I hiked those trails; mainly carelessness on my part for not really paying attention. With a gps phone app, when I started to suspect I was off trail, I could have glanced at it and known for a fact instead of going a little further to see if I saw an marker/blaze. That said, I've seen plenty of people break their phones on a trail and I drowned mine once in a deep pool where it was dead afterwards, so always have a backup.