we have about 25 ish beechjets--- it takes a few legs to figure that specific plane out so i always start out 1600, 1100, 1000,1000-- and tweak it as necessary.
ive also went in the advanced method and did things like start at an airspeed and decrease it 3 kts per thousand feet up to 43000'--- it seems to be failry accurate--- i took the long range cruise numbers and plugged them all in-- it took about 15 minutes of tweaking but its even more accurate than the hourly method
just rememebr if u only have one its easy, but it will take a few legs and an understanding of a multiple of variables to get accuracy like whats ISA, are you in aspen, and my favorite are you descending into PWK 287 miles out with chicago center/approach
only then ... can you tame,,, the mighty beechjet grasshopper