Elsebeth Lavold, a Swedish designer, uses a knitting machine to do the st st of a garment...and uses needles to do the fun part, the cabling and design work.
She divulged this on an Alaskan Knitter's Cruise my BFF and I took back in 2004. EL was one of our four knitting designers giving classes.
As for myself, I do everything by hand, and wouldn't think about getting a knitting machine to do my hard stuff (st stitch)! But EL is on a time crunch a lot of the time. She wants to crank out a garment to wear for an event.