"A non-precision approach is considered acceptable if the inbound track places with aircraft within a 30deg intercept of the runway".
Shunter,
You misunderstand that requirement.
What you are talking about is a design feature.
For an approach to be considered a straight-in approach then the final approach track -
the published one - must be within 30 degrees of the centerline. If it is outside that then it is a circling approach and circling minima apply.
When you are flying an approach the figure you need to apply is +/- 5 degrees for NDB and VOR.
You are not established on the required track unless you are +/- 5 degrees of that published track. You can not descend on final approach until you have established +/- 5 degrees and if you exceed that then an immediate missed approach is appropriate.
Regards,
DFC