What are the practical considerations you highlight When assigning a calendar for a project in Microsoft Project during shutdown managment ?

The shut down activities are carried out uninterruptedly in order to reduce the down time.
In most cases the working calendar and hours go beyond normal working days and hours.
So depending on the management decision Calendar is known to planner and he will prepare the calendar and assign that calender to activities accordingly.
It can be7 days per week or6 days per week and working10 hours a day or24 hours a day.
Prepare a copy of the standard calendar and modify it accordingly.
Save it and apply as needed.
You can have One Calendar for the whole project and different calendars for different activities but in case of Shut down Management a7 day24 hours choice is mostly used in oil & gas industry where three shift system round the clock is possible.
Business need and HSE play an important role in balancing the judgement for framing the calendar.