The most trustworthy formula is only as good as the data inputs. Wind, ISA deviations to temperature and pressure, aircraft weight, velocity at start of descent, velocity at end of descent, specific aircraft capabilities, etc., etc., etc. A complex formula is as likely to give as good consistant results as a simple one with a little mid descent correction required often as not for both.
I always found the 3 to 1 with a mile per 10 knot decel was ball park enough to add a little tail wind or subtract a little for head wind to, try dividing the wind by 3, a normal descent is around 20-30 minutes but the wind usually decreases as you go down. If it's really cold add a few, if it's really hot subtract .037 nm per degree K above 425 degrees. Then go back to the first calc. and compare.
BD