The technique you advocate is certainly valid however it requires more than a little experience to carry it off successfully and avoid e.g. a power on nosewheel touchdown - BOINNNNG! As most circuit training tends to be of ab-initio students the experience level is not there so it is by far safer to train for the go-around every time. With more experienced students it would be a good idea but how many people come back for more than the bare minimum of instruction (understandably,££) after they've qualified?