‘training’ as a countable noun

‘training’ is normally an uncountable noun, but in academia it is also used as a countable noun (e.g., “You need to complete these 5 District-mandated trainings by September 30.”), as a synonym for the longer expression ‘training course’. Merriam-Webster’s free online dictionary fails to note this sense in its entry for ‘training’.
keywords: errors and omissions, linguistics