Wow! You have to untwist the yarn every 20 stitches?
That seems like a lot!
Depending on how much knitted fabric you have on your needles, I mean if it isn't too far along, you could try this (I have done this before, too): stand up, lay your knitting on the seat, hold the yarn about 2 feet from the knitting, suspend the knitting in the air and let it twirl and spin as it untwists itself.
Ya know, sometimes when I've cast on a bunch of stitches I notice that the yarn inbetween the skein and the needle is all hinky twisty. Before knitting row 1, I hang the needle in the air by holding the skein up and allow the needle w/ cast on to spin and spin to untwist!
Am I making sense?