Recently I participated in the xiomi redmi note 3 flash sale.
I was really disappointed with sale.They showed that 32 gb varient is avaiable but when I clicked add to cart , it showed that waiting list is full.I clicked the add to cart immediately after the sale started ( within a second) . Many other users faced the same problem that I faced.
The time when yureka was launched , amazon was having same problem.so I recommend amazon to have sufficient stock before starting the sale for good customer experience