I think the only way to crack Nav is by doing it.
The technique observed on many PPL Skill Tests is "Point and Pray" which probably results from doing just that. The candidate sits there with a finger pointing at the map 20 minutes, occasionally making wild and illogical guesses, then somehow expects to finish up in the right place. No planning, no checks, no method, no clock, no accuracy and it would appear, bugger all instruction!