An NDB is a non-precision navigational aid. There is a requirement to make 'due allowance' to compensate for the effects of head/tail and crosswind effects when in the hold. And that is all there is to it.
But all the crap about 'gates' etc is something dreamed up by some who relish the idea of turning something very basic into something unnecessarily complicated. Usually FTO IR instructors on the edge of senility who last flew a real aeroplane in the days of Viscounts.
"...checking the needle is leading him onto his inbound track correctly during the inbound turn"? I was always advised to believe my calculations and not to pre-empt the ADF indications during turns due to the effects of dip.......