The first time I took it, I had been in the business about 15 years and found it to be very informative. Going in I was dreading the thought of 5 full days in a classroom, but the week flew bye. It was very informative as well as entertaining. I even took it a 2nd time 10 years later. It by far was the best class/seminar I have ever had.
We are a bit larger company with already established systems and procedures in place. The class helped us add and refine some things as well as validate other things we were already doing.
Also it gives you a chance to meet and network with fellow cleaners. There is a lot of value in being able to pick-up the phone and chat with someone you met in the class who might be going through similar problems, etc.
Finally the procedure manual you get at the conclusion of the class is worth the weeks time investment all in itself. You now have a procedure manual that you can use as is or modify it to fit your company.