Not sure if this has been discussed but it just dawned on me that JW's DO tith. Not with money but with TIME.
Bookstudy - 1hr
Theocratic Ministry School - 1hr
Service Meeting - 1hr
Public Talk - 1hr
Watchtower - 1hr
Field Service - 2hr (on average per week)
Now (being conservative), most colleges teach you that you have to study for a minimum of the credit hours per class per week. So lets add another 7hrs.
~Total = 14 hrs per week.
There are 168 hours within a 7 day period. Ten percent of this is 16.8 hrs. (VERY CLOSE, coincidence?)