Dear elodienyc,
The answer is always it depends......sure books give you about 70% of the information but information about how hard to press, where exactly are the body landmarks to look for ect, are sometimes hard to work out from a text book unless you are in the medical field. Also, it pays, in my opinion to have a physica routine hard wired ino your thinking as you will use these routines only in times of stress and you do not want to be thinking to yourself ....well what comes next...at an emergency you need to be briskly and smoothly flowing through the necessary steps.
I already know first aid so don't need to enroll but given that my maid/helper will be spending time with my 7 monther, I will be sending her to a first aid course, for both my baby's sake and that of my friend's babies (whom we will be spending time with).