I think it's holding over a specific point that I have trouble with. In order to do that I would need to circle over that point which I can't do when my hands are off the control column.
By the time I've drawn my line, measured the heading and calculated the eta approximately 30 seconds have elapsed. Although the aircraft is trimmed, most have a slight roll to the left or right which means by the time I've plotted the new course, I'm already passed my starting point and I've veered about 20-30 degrees off track.