I heard that there is a 'trick' to getting a certificate for free ($) on Coursera: First you just review the course which is free of charge, and then after you'

I heard that there is a 'trick' to getting a certificate for free ($) on Coursera: First you just review the course which is free of charge, and then after you're done with it all you start the free trial. Now you have 7 days to finish up the courses which shouldn't be a problem due to the reviewing. So that could in part explain the short completion times, although I'm not sure how many people use this 'trick'. Coincidentally though, I've learnt about this trick in relation to the exact course you mentioned (deep learning.)