I almost always undo the auto-reschedule that happens when I move things onto calendar. I'd like to be able to optionally anchor certain tasks/time-boxes as needing to start and/or stop at a particular time. Ideally auto-reschedule would respect this when possible, and when impossible, would surface a warning that my calendar constraints were unsatisfiable.

(In the meantime, I know I can turn off auto-reschedule, and sometimes I do, but I like tasks to indicate that they were finished early on the calendar so I leave that on.)