In order to allow casting of two floors each week, three days per floor, a slight upgrading of the concrete design strength was necessary, from fc'=4000 psi to 4600 psi.
The more subtle advantage of post-tensioned construction is the resulting flatness of the slabs, making it easier for the finishing trades to install drywalls, shower bases, bathtubs and tiles, kitchen cabinets, and to align trims and moldings.