My first 121 carrier the aircraft was hand flown to something above 10,000 feet. On decent the A/P was usually disconnected on slowing at 10,000 feet. When checking out on the 74, my check captain hand flew it to FL350 and continued to hand fly it for the next ten or fifteen minutes. There was never more than a few feet divergence from 350. We had a long discussion about hand flying and he encouraged hand flying at cruise altitude. He said a one degree attitude change at M0.8 will result in a 800 foot climb or decent. That is were you learn to make tenth of a degree corrections, note that it was always raw date. As I waited my turn for up grade, I would, traffic. work load allowed, hand fly for the first half hour or so. More than on captain would ask, you want the A/P now.