https://en.wikipedia.org/wiki/Instructional_design

For an example of a training system design approach that has been taken to an insane level of detail and organisational complexity, take a look at the UK MOD's version, the Defence Systems Approach to Training.

https://assets.publishing.service.gov.uk/media/652fac8692745...

For competence retention, have a look at

http://icicte.org/ICICTE2015Proceedings(Papers)/7.2%20Cahill...