A few weeks ago I was on a two-day trip in an unfamiliar forest. I used a really nice free application called "Maprika" to combine my phone's compass, GPS, and some crowd-sourced trail maps and chose a site to camp that was well off-trail. The first night there was quite a bit of rain. My shelter didn't leak but the humidity messed with my phone and charging brick and put the phone in a useless state.
When the rain let up late the second night I decided to move camp closer to a water source and to my morning pickup point. It was very difficult to get oriented in those flat, dense woods from my off-trail location. I was glad I had a paper map and a little clip-on compass on my watchband. I found a pipeline trace that was on the map and was able to plot a longer but surer route back to the main trail from the pipeline and a few side trails. The watch was a big help in guaging distance traveled, helped out by the flat terrain. Even the tiny compass was enough to match up subtle turns in the pipeline trace with absolute position on the map. I'm sure I would have figured it out without the map and compass in the daylight, but it would have been really frustrating at night.
Redundancy in important systems is important, and it's easy to forget how important some things are until they're not immediately available.