John Hearne's presentation was particularly interesting. It's a vital subject to know how much practice you need to retain skills. It's actually different than you might imagine.
The old saying I learned was that amateurs train until they can do it right once. Professionals train until they can’t do it wrong.
The results clearly show refresher's are necessary and overlearning is king.John presented some data from a study where a skill was learned by some and over-learned by others. There were 3 groups: adequate learning (passed at end of initial training), refresher (re tested/re trained 4 weeks later), and the overlearned group. For the overlearned group, the standard was that it if took them 30 reps to get the skill right, they did 30 more reps *after* the skill was mastered.