N5396S,
Two different animals here, a non-TERPS'd home designed approach versus a usual ATC procedure to an operational advantage, that is, expedite traffic.
foxmoth,
While your example has some validity, air discipline requires as accurate as possible observance of established minima. If 1,999' is ok is 1,900'? When does one stop descending? All the errors in the error budget are not terrain, but instrument error, Venturi effects over mountainous terrain, ground reporting errors, etc.
GF