I'm actually teaching English in Vietnam at the moment and was asked to assign homework, after I read an article about how students here are overworked/over educated, and as you pointed out much of the extra work makes little to no sense and pupils are becoming stressed, depressed, and sometimes where they feel they aren't meeting the ridiculous academic expectations, suicidal. The classes I teach are already extra curriculum evening classes which includes weekends, I basically refuse to give then anymore homework and try to make lessons they enjoy enough that they want to be there. If I do cave into the demand to set homework I will ensure it is something that allows the pupils to relax and forget about education for a while.