I took the course a few years ago as it is mandatory here in Ontario for anyone using a chainsaw for anything other than personal use. There are various courses offered here in the Province, and only the written exam is standardized. A competent operator with a good knowledge of saws and felling could easily pass the written test, and the practical test is strictly subjective - it is up to the instructor to decide if you pass or not. That all means that there are certified courses that are only 4 hours long with basically zero practical instruction. The course I took was 3 days long (1 day in classroom, 2 days in the bush) and was offered through Algonquin College in Haliburton. Pretty good course and I am sure even the experienced guys there re-learned a few things the may have forgotten over the years. Lots of Hydro One guys there, and lots of landscapers. There were 3 girls in my class, and that leads to my one concern. None of those girls had ever held a chainsaw before. Since you had to provide your own saw, they all brought borrowed saws that they new nothing about. One girl's saw wouldn't even run on the last day and she spent the whole day dragging brush and piling wood. 1 girl was a fast learner and at the end of the 3 days was doing not too bad. The other 2 were just not cut out to run a saw and required constant assistance by the instructors. And everyone passed!
So while I thought the course was worthwhile, I certainly wouldn't hire or insure anyone based solely on the fact that they had passed a certified Chainsaw course, since even the most incompetent of attendees seem to get a passing grade.