Some evidence in favor. https://journals.sagepub.com/doi/full/10.1177/2158244018811024

Some evidence in favor. https://files.eric.ed.gov/fulltext/ED427772.pdf

Good insights here, especially for use in education. Spacing likely doesn’t help for all skills https://www.aft.org/periodical/american-educator/summer-2002/ask-cognitive-scientist

Not sure if this is even a study, but another vote for Spaced Learning in education: https://www.diva-portal.org/smash/get/diva2:854586/FULLTEXT01.pdf

More about retention, but likely has implications for learning: https://medicine.wright.edu/sites/medicine.wright.edu/files/page/attachments/Kerfoot%20etal%20spaced%20education%20retention%20knowledge%20MedEduc2007.pdf

Uncertain implications ( https://www.researchgate.net/publication/271076930_Distributed_rereading_can_hurt_the_spacing_effect_in_text_memory)

https://notes.andymatuschak.org/z3d6dFhTA5zTmykZ3zh4Y2vCw3aVbUxRiQQcc

https://pcl.sitehost.iu.edu/rgoldsto/courses/dunloskyimprovinglearning.pdf