It should be possible to plan a workorder over several days - e.g. 2 hours every day for 3 months or 2 hours every Wednesday for the rest of the year. Today, there is only a limited functionality in the planning board to plan this kind of tasks. The same functionality should be possible during advanced planning in d365.
This is something that one of our customers has requested as well. If required, I could provide a user case from them.