There is a lot of good background material in the FAA manual and it's free, however there is also an enormous amount of FAA specific information and guidance in there as well as techniques (look at attitude control and holding for example and you will find different methods described which really need some practical instruction to support). To the uninitiated, this 'wealth' of information will likely prove confusing and overly time consuming without structured guidance.
My opinion based on experience as a UK ATPL/IRI and FAA CFII.
Out of curiosity sapperkenno, where did you do your CBIR?
Last edited by Reverserbucket; 5th Jun 2017 at 16:30.