I tend to use 4" as a standard carry, as I can get away with it no problems here. Millie has lots of belly and a wide handle to grip.
My main pair(endura on left, millie on right) can be cycled quite fast for the size. just muscle memory. Given human error(0.16sec avg), try this:
have a friend time you(the human error part). Assume the position(hands on wall shoulder height and width apart, palms on the wall, feet shoulder width apart), have your buddy start the time when you hands move. Reach down to your front pockets, and draw to ready(whatever the grip may be you choose to agree on). have them stop when you have knives in grip of choice. Do it again, but draw to ready, and then reverse(close, replace, hands up again).
I can do out in 2, out and back in 5. Given average human error, thats 1.68-2.32 and 4.68-5.32...
Who needs and auto at that rate?
And going by the still healing mark on my left thigh, the millie does damn well as a stabbing tool. stabbed about 1/2" of blade into my leg in febuary.