You're right JJ. Ironically, it was this tailoring of evidence and his pathological inability to admit to any wrong doing whatsoever that led him to fall into the prosecutions trap.
The police psychologist, Major Bronwynn Stollarz played a blinder here in advising Nel to keep switching the themes of the cross-examination. Liars are often unable to work backwards. Witnesses are often coached to tell their story from start to finish, and this can make it difficult if during cross-examination when they are asked to repeat it out of order or in reverse and especially if the prosecutor keeps jumping from one theme to another. Stollarz had also researched all the background collateral information on Pistorius and knew he had a history of refusing to take responsibility and passing the blame on to others.
So right from the very beginning Gerrie Nel asks him to take responsibility for the death of Reeva knowing full well he won't because he can't. "You killed Reeva Steenkamp, didn't you?" he asked at the start of questioning. "You made a mistake? You killed a person. You killed Reeva Steenkamp. Say it. Say I shot and killed Reeva Steenkamp." He couldn't, instead he replied "I did, my lady."
Nel accused him of "not listening" to his questions and telling the court well "rehearsed answers" over and over. Pistorius told the court he was telling the truth and was under pressure because his life is "on the line".
"Please answer the questions, don't argue the case, you will get into trouble." From then on Pistorius was in defence and denial mode and never conceded a single admission of guilt. He blamed the police, his then non-existant GAD, his friends, his own father, even his own defence team. He was never to blame.
Then finally when Nel asks him if he intended to shoot at the person behind the door he denied that too and unstitched the whole defence so carefully worked out. No PPD, just some unintentional, unexplained accident. Both at the beginning and end of the cross he could not bring himself to admit culpability of any kind. His hatred of Nel and his ego saw to that.
I know some people thought Nel was inferior to Roux during the trial but I think the PT had Pistorius sussed from the outset and let him hoist himself by his own petard. His hatred and contempt for Nel by the time Nel had finally and tortuously brought him to the crucial question was such that he was blind to the careful coaching of Roux and he was so determined not to concede a single thing to the loathsome Nel he ensured he would be forever remembered as a lying, cowardly, unrepentant murderer who would say anything and everything to save his own skin.
Paradoxically, his pathological inability to lose, his fear and loathing of weakness, his must-win mentality that had served him so well in his athletics trials was ultimately his undoing in the most important trial of all. His greatest strength was also his greatest weakness.
I remember that moment well it was very dramatic at the time and even though seconds it seemed to last for an age. I think Nel just realised he'd either frozen or was playing the drama queen and wanted to crack on with the cross-examination. Unlike those of us witnessing a live murder trial for the first time and influenced by TV dramas, Nel was surely too experienced to expect Oscar to simply crumble and confess. He afforded the accused the appropriate time and got back to work. 
