There is no consistent pattern in the evidence. A 2010 systematic review concluded that the 4×4 pattern seemed to produce higher overall achievement than traditional schedules, though this may mask differences between subjects. More detailed analysis suggests that in science the A/B block scheduling approach resulted in higher results than traditional schedules (two to five months of additional progress). In mathematics and English the evidence was unclear with studies showing both better and worse results for any type of block scheduling compared with traditional scheduling.

The evidence suggests that how teachers use the time they are allocated is more important than the length of lesson or the schedule of lessons, and hence that the introduction of block scheduling is unlikely to raise attainment by itself. It may also be that when different timetable patterns are introduced, the changes will only be beneficial if teachers alter the way they teach to get the best from the time allocation. Teachers and students often perceive that timetabling changes are beneficial, especially when it appears to increase one to one interaction. However, these perceptions are not clearly linked with improved learning outcomes.