The NFL average that a NFL QB has to get rid of the ball or get sacked is 3-4 seconds. Yes there are certain times that a QB will have longer but I am going by a average. I know of McNabbs 14 second scramble so please don't bring that up but he is in a league of few men.
This is why the dropback and the need for a primary WR is needed. If a QB drops back and there primary is covered and there 2nd a 3rd after a quick glance is covered they will throw it away.
The only concern I have over this is a Nano Blitz. I would hope there is a way to bring your RB & FB up closer to the line to help block in this case or you will see this........
Look at the 4:10 mark of the video....
http://www.nfl.com/videos?videoId=09000d5d80d1d91b