15-20 the key to 20-20 or 10-15?

In the wake of England's demise in the World T20 i have been thinking about what a successful strategy might be to get a decent score in the game (seeing as England need a strategy they are welcome to use mine!)

Now orthodox thinking is that you keep wickets in hand for as long as possible for a final assault at the end. However i believe this plan is flawed in T20 cricket. These wickets in hand will likely be coming in against the best bowlers in death bowler mode and will have to try and start whacking from the off. Launching an assault in the final 5 overs is too late.

Perhaps the 10th to 15th overs are where the assault needs to take place. Having had an early whack in the power play maybe England need to use overs 7-10 for consolidation and then whack out against the bowlers in 10-15 which usually are the second-string seamers and the spinners. With momentum gained then the final 5 overs can be a continuation of the assault, or if there are not many wickets left a run-a-ball cruise to the end.