Allow me to rephrase the second paragraph:
On a flight from anywhere, to any destination where the airport elevation is above 6000 feet; we will set 6000 in the LAND ALT window. At initial descent or approximately 20 minutes prior to landing, we will set the real, actual destination airport elevation in the LAND ALT window. There is a cruise altitude (I can't name it exactly but my estimate is FL360) above which the auto pressurization controller reaches 8.35 psid and it must increase the cabin altitude on schedule which will mean the cabin altitude goes above 6000'. Therefore, until the cruising altitude exceeds FL360 or the LAND ALT window is reset for top-of-descent, the cabin will be 6000' and the passengers will be breathing easier.
Put another way, on a flight from JFK to MEX (MEX field elevation 7300'), with a cruising altitude of FL360, we could have the cabin pressure at 6000' instead of 7300' for 5 hours with no cost to the operation. Those with marginal cardio-vascular health will benefit most, but all will feel better during the flight.
Pcars