Answer:- Distributed practice
Explanation:-
Distributed practice is the mechanism in which a person tends to split practice into short session over long duration of time unit so that it can be learned .This spaced practice is used for long study.
According to the question, Cobin is unable to remember textbook material if e studies for 30 minutes every nit for six days consecutively because of lack in disturbed practice .He can learn more through studying three hours at nights just before exam for better remembrance.