I like Jeff's system, and as always......I have to wonder just how fast the wheels spin in that guys head!
If I were put in charge of splitting classes, I would have to go with the Excel method.
Class size would be determined mostly by show ring size first. How many calves will comfortably fit in the ring at a given time. I hate an overcrowded show ring, and I hate a division of 16 that get split into 4 classes of 4 calves when the ring will hold 20.
If there are 160 in a breed or classification, and we want a champion drive of 4 + 4, the splits become pretty simple. The tallest of heaviest 40 are one division, next 40 are a division, and so on through the 4 divisions. If the ring holds 10, then the divisions get split 4 ways by height or weight. If the ring holds 20, then the divisions get split in half.
I would just keep it simple, and minimize the number of classes as much as possible.
The biggest reason I would go this way is time. Like another member stated earlier, I could have the entire show classed in about 5 minutes.