Consequences for Behavior-Informed by Learning Theories

Since in the future, I plan to work with children doing behavior interventions, I chose to focus on behavior.  I asked one of my friends with a 3 year old boy (very advanced I might add) what she does as a concsequence when Ethan misbehaves. She said that in a case where he hits or is aggressive with his little sister (20 mos.) he goes into time out for three minutes.  I asked her why she does this and she said this is due to the fact that "he knows better." She says he should know better since he has been punished before for the same action.  (CLT-she seems to be drawing on past knowledge). She also claims that he does not like time out and that this has been an effective discipline before. In the past in timeout, Ethan would throw a fit for about 2 minutes, then look at her and say "mom" when he is done tantruming. She asks him, "Are you all done" and he says "A..Yeah." (CLT). When I asked her why she originally came out with the concept of timeout as a consequence she said she had seen this be effective for other children and mothers. (SLT-she is looking at the more knowledgable or experienced peer for a better understanding.)