Currently, if user set multiple tasks so that they start at the same time and work in parallel, user can make assignments that exceed the user's capacity.
For example...
Suppose three 9-hour tasks start tomorrow at the same time, and one person working 9 hours a day works at the same time parallelly. If you think about it normally, each task will be completed in 3 days by proceeding for 3 hours per day. However, in the same situation with the current system, one person works 27 hours a day and is assigned to complete all tasks in one day.

For example, in the above case, be able to schedule all tasks in parallel for 3 hours to complete in 3 days, just as normally schedule.