If you show a student how to use the navaids prior to him completing his solo navexs then you don't ever know if the only thing getting him around was the navaids.
If he is using them he is cheating himself and setting himself up to fail the skilltest.
Even if he does know how to use them I don't like the idea of Bloggs being out in the open air for the first, second or third time with his head down, frown upon face, twiddling with the nav kit.
Its a recipe for spiral dive, stall or collision.
What he should be doing is drawing a circle and then following the Lost Procedure.
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