My wife a teacher, the problem is students don't study for the test and know they can make up the test(this is the current policy at Visalia Unified school district). They then know what is on the test and then look it up. If the teacher has 2 or 3 copies, they just keep retaking it. It's a lot of work for Teachers to make up a new test, just so the student can keep retaking without studying. It a wake up call in High school when they tell the teacher, passing it out, and they say I"ll make it up tomorrow because I didn't study, and the teacher goes, no you won't.