Give the best summary of the second paragraph.

Directions: Answer the given question based on the following passage:

There is considerable evidence that time is a factor in learning. There seems to be something going on during periods of rest, particularly immediately following practice, that influence the consolidation and retention of that which has been practised. We do not know just what goes on or how it operates, but the evidence is quite clear that some type of spacing of repetitions facilitates learning and has an even more favourable effect on retention. 
One experimenter set out to discover whether the method of spaced repetitions was more effective than that of massed repetitions for the purpose of learning ordinary meaningful material. Thirty short selections in history and the same number in economics represented the material to be studied. Each assignment was read through five times, either at one sitting, one right after the other (massed reading), or once a day for five successive days (spaced readings).  Subjects and conditions were so rotated as to cancel out practice and fatigue effects for the two conditions. At varying intervals after the original readings, the subjects wrote all that could be recalled of the selections read. The amounts retained after varying time intervals were also determined.
The results show some interesting differences. When tested immediately after the original readings, 66 per cent of the material read five times in one day was recalled as compared with 64 per cent of the material read once daily for five successive days. This difference is not significant. When tested two weeks later, only 13 per cent of the material read five times in succession was recalled, whereas 47 per cent of that read daily for five days was reproduced. After one month, 11 per cent and 33 per cent respectively, were recalled (Austin 1921). In this particular experiment, for immediate recall, massed repetitions were as effective as spaced, but for retention over a period of time a different story is told. The material learned by the massing of repetitions is forgotten much more rapidly. Two weeks or a month after the original readings almost three times as much of the material read daily for five days is recalled as of that which was read five times in succession.
Not all the experimental studies on this topic have shown differences as marked as those cited, but the overwhelming majority has shown an advantage of some form of distributed practice as compared with the massing of repetitions. There is some evidence that the advantages of spaced repetitions are greater for the learning of more difficult than for that of very easy material and that they are greater for relatively meaningless as compared with more meaningful material. While it is hard to make any blanket recommendations, it would seem that for most forms of motor learning the spacing of repetitions is better than massing them. In most rote ideational learning, spacing probably has an advantage over massing. In the development of concepts and in problem solving involving common mental sets, the massing of practice is best, but where a shift in mental set is required spacing has an advantage. (Sawrey and Telford in Education Psychology)