The task details of scheduled tasks cannot be modified once created, only the computer scope and the schedule can be modified. The task operations details such as reboot delay, planning mode, inventory rules, deletion threshold, etc can only be viewed.
This make it very difficult to, for example, test a schedule in planning mode since the task has to be completely recreated for production use in order to disable the planning mode flag, potentially introducing errors that weren't there originally. It also means that a task can't be updated when the requirements change or when problems occur without tediously recreating the entire task from scratch.
