When I was working at the refinery, I wrote safe work permits which ranged from regular duties to hot work, confined spaces, elevated structures, etc....
There are several levels of confined space permits and usually you have to write so many of each type before you can go up to the next higher level, usually a year or longer and 10-20 of each, the permit writing classes were ok'd by OSHA or they would not have existed.
I don't know what level of permit writing class they are offering but when you are dealing with people entering confined spaces there are a lot of factors involved like using 4 and 5 gas meters, calibrating them every day, taking readings every 15 minutes, having the hole watch trained, having a rescue pre-plan and going over it with the rescue workers that are on-site or the local paramedics or fire department, etc.....This was at the refinery so there was always checking of voc's, lel's, o2, etc..... to make sure that it is not only safe to go in but to make sure that there is breathable atmosphere in there for people to survive.
They don't mention what extent the confined space training is but when you look into it, there is several levels and it takes time and many, many permits to go up levels in permit writing along with time in between each level, sometimes a year or longer.
Just a FYI, not trying to bash.