The 6-credit-hour exclusion is a 1-time exception that lets you drop up to 6 credit hours and still keep the benefits you received up to the day you stopped attending classes. You don’t have to show mitigating circumstances to keep those benefits. 

You can use the 6-credit-hour exclusion only once, even if you drop fewer than 6 credits. So you can’t use it to drop 3 credits, then use it a second time to drop 3 more credits.