We got kind of lost in Ponferrada. The issue probably wasn't the lack of arrows, but just that the arrows compete with a lot of other things for your attention - that combined with a lot of streets and possible twists and turns makes it easy to miss an arrow. We had booked a hotel in Ponferrada for the night that was right on the path - got lost on the way to the hotel and were not in the mood to traipse around looking for the place. A taxi appeared, so we hailed it and it took us to our hotel - The Camino Provides
The next morning we had trouble finding the route out of town too, but we were fresh after a good night's sleep, so it wasn't a big deal - we found our way out.
The route out of Leon was another place where we probably would have gotten lost, except that there were plenty of other people walking out of Leon that morning, so we just went with the flow.