It has been many moons now since the little kielbasa first learned how to sit on command. I remember the concept was actually one of the harder things for him to learn at first, til one day during our AKC good citizen training class when he was learning to cope with supervised separation, he apparently plopped his tushie down for the instructor's helper while I waited for him in another room, and that was that. With hind legs parallel, square on the ground and neatly tucked under, sit was forever imprinted as a very quick tushie plop, with no allowance given for sloppy side rump sitting, no chance for both hiney legs to peek out from one side or the other.
But since our class five years or so ago, we've both gotten a little lax in our training, and though the tushie plop remains a signature move for a sit, Baxter's little hiney legs and toes often peek out the front, and he becomes my little Eeyore. :)