Is it permissible to shorten prayers for only three days, or is it not permissible at all, when residing in one city and working in another 360 km away, with permanent accommodation at the workplace and a work system of 14 days on and 14 days off?

If a traveler intends to stay for four days, excluding the days of arrival and departure, their travel status ceases, and they are not permitted to avail themselves of the concessions of travel, such as shortening prayers (qasr) or combining them (jama‘), this being the view of the majority of scholars. If you intend to stay at your workplace for fourteen days, then you are absolutely not permitted to shorten or combine prayers, because you are considered a resident from the moment you enter the town.