On 9/3/2003, I wrote.
There are two kinds of people in the world. Those who divide people into two kinds and those who don't. Corporate seminars have to be more complex, though, so they divide people into four groups. The details vary from system to system, but there are always four.
Four is a good number for a one day seminar or workshop. You have time for definitions and anecdotes in the morning, with testing to see which category you occupy just before lunch.
After lunch you can gather into your four groups for a few group exercises, come back to the whole group to present one exercise as a group, and then talk about difficulties in communication caused by differences in style.
You get donuts in the morning and coffee and bottled water all day. There are two fifteen minute breaks and half an hour to an hour for lunch, depending on how close the restaurants and snack bars are.
People walk and stretch and chat during breaks. (Updating for today, a varying number will be on cell phones, making social connections or checking on their work back in the office.) The bathrooms down the hall and the drinking fountains are in demand. People are usually from the same company or agency and spend time swapping stories and questions about different departments.
But if you want to earn more than a one day seminar can bring in, you have to divide people into more than four categories. The systems that I am familiar with that do this are enneagrams (9), astrology (12) and the Myers/Briggs assessment (16). Unless things have changed, the Myers/Briggs is the only one that most businesses and agencies will plunk down cash for.