- On-campus courses can sometimes be taken part time
- “An hour is usually 50 minutes”- this is not true of CELTA courses, where some lesson bits you teach will be as short as 20 minutes, but the grand total will be at least 6 full hours. Not sure about other courses.
- “Check if the TEFL training program has any Professional Membership, such as IATEFL” – any school can join IATEFL or TESOL just by paying the fee, and IATEFL will not check the quality of schools or courses. I agree, however, that not even bothering to join professional organisations can be a danger sign of a slack school or course
- I think the word “chain organisations” could be confusing when talking about CELTA, Trinity and some TI courses. The courses and schools will not be owned by Cambridge or Trinity, although it could be offered by an actual chain of schools like International House or the British Council, which can be an additional guarantee of a reaching a certain level of quality
- “The often also have contacts with local schools to get you a job”- but that might not be any use when you want to move onto another country where no one has ever heard of that particular TEFL certificate

This might interest readers who enjoyed your post:

http://www.tefl.net/alexcase/articles/tefl-qualifications/qs-tefl-course-provider-celta/