Where do all the essays go in college? At my college I worked in the back room shredding graded essays from various subjects for hours. 

Some of them were very good and seems like a gross waste of data and labor.
I wonder is this the policy of all colleges? 

https://law.stackexchange.com/questions/40595/can-database-be-collected-from-essays-written-in-college
Colleges have to keep everything that influences grades of students for a certain time in order to resolve disputes over grades. In our case it is 3 years.