Learning a new Move

For me even the smallest change seems to be hard to make. During my lesson given one small but significant change to work on for the next week. Drills are prescribed to work on. The first practice it seems like I will never get it. The second practice I can do the move but other things change for the worse. Practice 3 and 4 are used to cement the feeling of the new change and get rid of all the other things that crept in. So far I have been able to achieve the change before the next lesson and we go on. Practices at golf tec are normally about 45 min. During that time I general hit around 20 balls lots of swings with know ball an lots of time review the last swing on the video and sensor monitors.  With out the feed back it would be much harder to get were I am going.