We are dealing with mechanical gadgets, any of which can be broken or fail for a variety of reasons. What should occur is that the user will be well versed in the proper use of the compass and map, be aware of potential problems, checking and constantly verifying. Backup strategies and ploys are always useful.

How many ways are there to determine north if your compass is on the fritz? (and the hoary "moss grows on the n side of trees" doesn't count)