Again, defensive batting is not simply a cure all for poor technique. A good bowler can get plenty of edges from defensive batting, particularly spin bowlers.
Let's just take any test match, how about the last Adelaide test:
Here
Steven Smith is bowled playing quite a defensive stroke.
Stokes takes an edge off a push by Haddin, the wicket is overruled due to overstepping the line
Siddle edges it playing defensively on the back foot
Cook knocked over playing defensively on the back foot
Prior edges it off a defensive shot
Johnson demolishes the stumps as Anderson plays defensively
Johnson takes off stump as Panesar plays defensively
Rogers edges off a defensive shot
Panesar bowls Clarke as he tries to play a defensive stroke
Siddle takes the top of off as Pietersen plays defensively
Root edges it playing defensively
Stokes edges it playing defensively
That is from one match.