How very gamist of Gygax.
The inch notation is meant to represent tens of feet indoors in 1E and tens of yards outdoors.
The 1" corresponds to 10s of feet/yards - so 150 feet per unit of time in a dungeon, 150 yards outdoors.Continuing to use the Banshee as an example, it's speed being 15", would then be read as 15 feet in a dungeon, and 15 yards outdoors?
I was going to post this too!One note is the 1" is always 10 feet when used for spell area of effects whether indoors or outdoors.