We keep it on the mike as much as possible because hand steering requires calling out a second AB for watch, something we try to avoid as it leads to fatigue and work/rest peroid problems.
The ship autopilot aka the iron mike uses adaptive auto steering, in other words it learns how to steer, the longer its engaged the better it does. If the ship goes off course the “off course” alarm sounds and the normal response is to switch to hand steering to get it back on course and than switch back to auto. The issue with that is the auto-steering “forgets” what it has learned about course-keeping and has to start from scratch. What that leads to in heavy following seas is a constant futile switching back and forth between auto and hand.
It’s sometimes better to input, not the course you want into the autopilot, but to imput a course order that results in maintaining the course you want, and then, as the autopilot starts improving course keeping it will slowly change from the desired course to the input course. As the course-keeping slowly improves the input course is gradully changed to more closely match the desired course.
For example, say your are running south down the U.S. west coast with a big sea/swell running from the NW or NNW. You want to steer course 180 but the ship is yawing around the course of 190. In this case the auto pilot is set on 170, which will result in course-keeping of 180. But as the adaptive steering starts learning to steer it will slowly work from 180 to the ordered 170 so the input is has to be gradually changed as required to maintain 180 (170, then 175 etc).
Other autopilot settings may have to be changed as well, max rudder, off-course alarm.