I've been doing a few transfers lately and none of them show up after 6. The last one I did wasn't in until 9 confirmations had shown up. One before I think might have taken 11.
When testing was performed so as to have the correct measure for the Wiki page, there were inconsistent results between six and seven. Blocks are being generated quite quickly at the moment, due to a lot of additional capacity having come online since the last difficulty adjustment. It's entirely possible that the exchange also has imposed a minimum wait for based on a time clock (e.g., 1 hour) as well.
If not, perhaps the exchange is having trouble handling the volume in a timely manner.