I believe you're learning to react. You're never going to get the set up you would in dojo (obviously). But you do get access to basic techinques... In the example you talked atemi and then take the atempted block into Ikkyo. I see the practice in the dojo as a more learning of priniciples more than techinque. You learn how to move, you learn the feel of the techinque, and you the proper set up for the techinque this trains to react, if you feel/see/hear/ this than do this. If the arm goes up to block take Ikkyo. If the guy is bull charging you trying to tackle you take Keiten Nage....
Just a newbies thoughts that haven't been tested outside the dojo