Because of the importance of surface area, the size of your towels can make an impact on the performance of your towel rack:
Oversized towels and bath sheets are often considerably larger than a standard towel, and will definitely need to be folded properly to fit on most of the mid-sized racks. It is important to note that these larger towels end up being thicker when folded, and can decrease the efficiency of heat transfer from the bars to your towel.
For some models, like the Radiant Collection, hanging more than two towels can cause heat to be trapped, overloading the rack and potentially causing any residual soaps in the towel to towels to become discolored from residual soap. Always refer to the included user guide for directions the amount of towels a particular rack can hold.