Does Glenn doman's method works? How about heregu or shichida? LO 15mo now

my 2kids are with Heguru when they are 19months old. so far for elder son he is not bad in his learning but attention span is still.. shaking head... can't sit still. the younger one who is going be 2yrs old seems to be able to learn pretty fast in following us the way we talk. so not sure if is due to exposure to this training program. but I feel if u can afford then can give it a try