Dhoni is quite aggressive with his declarations AFAIK.
Most recent example:
http://www.espncricinfo.com/west-ind...ch/489227.html
Left WI with a target of 280 in 85 overs, 1/0 up in the series..
I just think teams are too risk averse when it comes to declarations, because they just dont want to ever lose a match that they declared.
I agree with Brickie in that the best declarations are ones where you have like a 2% chance of losing, because I think the added time adds significantly more to your chances of winning. So if by adding a 2% risk to your game you're 10-15% more likely to win it's worth it.
Try to compare how many times you have seen the opposition 7-8 down at the close of play on the 5th to them being 350/3 scoring at close to 4 an over needing 100 more to win. An extra hour or so added is gonna help the bowling side a ton more than it helps the batting side, and when India are already handicapped in thier batting no need to be afraid of monsters in the closet.
Btw I'm not saying England can't win it from here 2-3 quick wickets and we could be toast, I'd say they're 40% to win it from here.