Efficiency is getting used to do the shortest easiest move that will end the confrontation, hitting the most effective and efficient pressure point.
If you train few times a week for years with the goal of choking or creating an armbar, or get to the floor, these training habits will stick with you and will not easily get rid of in a time of self defense conflict which may take only few seconds.
While your confidence will be great from the training it might be false, since you are not accustomed to deal with more efficient opponents. An efficient opponent,does not waste time on a Sports Match but instead is looking to hurt you quickly with disregards to your safety and life.
The efficient athlete is in most cases not an efficient reality based fighter!