High speed palletizing is an extension of the original dedicated palletizers and unitizers developed in the 50's. When pricing palletizers, speed is usually the primary consideration. However, higher price does not always equal higher speed.

One of the primary rules of palletizing is that the more cases per layer, the higher the speed. So, a machine that handles a 12 case layer at 36 cases per minute, may have a limitation of 12 cases per minute at 4 cases per layer. Or, in other words, the palletizer can do 3 layers per minute, if there are a lot of cases per layer, the palletizer can palletize many cases per minute. However, if there are only a few cases per layer, then the palletizer’s true speed is slower.

Source:http://www.material--handling--system.com/high-speed-palletizing.htm