Several studies have pitched the different learning schedules against each other to test which one is more beneficial for knowledge maintenance. Taken these different findings together, research suggests that expanding and equal learning schedules often lead to similar test performance and contracting learning schedules are usually found to be inferior compared to the other two.

Interestingly, the time between the last review session and the final test seems to affect the optimal learning schedule. In a study by Kuepper-Tetzel, Kapler, and Wiseheart (1) participants studied vocabulary using an expanding, contracting, or equal learning schedule. Afterwards they were tested on the vocabulary on a final test either immediately, 1 day, 7 days, or 35 days later. What they found is that for the immediate test it did not make a difference which learning schedule was used. For the tests given 1 day or 7 days later, a contracting learning schedule outperformed the two others (a finding at odds with most previous research). However, on the test given about one month later, expanding and equal learning schedules led to better results than the contracting learning schedule. Thus, it seems that if the goal is to maintain previously-taught material for a long period of time, we should either adopt an expanding or equal learning schedule. For short-term successes contracting learning schedules can show benefits.

However, it needs to be pointed out that previous studies have often failed to show any benefit of a contracting learning schedule. One feature of the just presented study was that participants learned the material to perfection during the initial learning session. A very recent study by Toppino, Phelan, and Gerbier (2) revealed that indeed the level of initial practice plays an important role in determining which learning schedule is most beneficial: They showed that when initial level of practice was high (participants took practice tests with feedback), then it did not matter which learning schedule was used. However, when initial level of practice was low (participants reread the material), an expanding learning schedule outperformed all other schedules on a final test 2 weeks later.