Not if the knowledge and perspective he can only gain from that walkabout is part and parcel of the training, I would think.
I think a much simpler reason exists: Harry did not, technicaly, lie to Mab. I remain convinced that, when Harry dealt with Mab, telling her that he had come to deal in good faith, he honestly believed he was telling the truth. That's the whole point of having Molly remove the memory of contacting Kinkaid - so that he could lie without lying. Harry understood that he would be willing to serve Mab, become the winter knight, to save his daughter, and took steps to prevent that, guided by the shadow. When he told Mab that he would not try to cheat her by killing himself, he was unaware that he had, in effect, already killed himself.
Similarly, I think we can assume that Harry has not, in fact, been proven to be willing to kill himself. The central plot point of GS was, after all, that Harry's free will had been compromised when he chose to kill himself. And while Mab might not care about or understand the discintion between an action and a choice, I'm pretty sure she understands the concept of having one's actions manipulated. Though i doubt she knew about the angel beforehand, it's plausible that Uriel has told her.
Another thing: you claim that mab used elaborate word play to pretend to be in oppostition to Uriel while actualy working with him. For example, that while she says that "had he been wrong ect. ect," It's possible that uriel simply could not have been wrong. I'd disagree with this view. The nature of the future in the Dreden files does not seem to be set in stone. In DM, we see an angelic prophecy be wrong/thwarted, and Uriel himself claims that freewill can always change things. Now, it might be almost impossible for him to be mistaken, but if it weren't a possibility, if it were not actually possible for Harry to, say, make use of Uriel's offer to join captain Jack and the others, or to simply make bad choices and overspend himself, not only does free will loose its meaning, the story becomes boring and trite, as conflict loses its value. I believe we are seeing the real thing when we are led to believe that Mab is genuinely displeased with Uriel.
That said, I do believe that Mab went along with it, probably grudgingly, and that she did, in fact, gain an asset from the whole ordeal: she got a more powerfull, willfull and headstrong knight. I think Mab values obstinence, pride, and willpower over obedience, as we see both her and her mother compliment and expect Harry's resistance, and in fact enjoy it. It is after all after Harry recieves an earfull of truth from Uriel that he challenges Mab again, promising to smite her foes and lay low her enemies, and threatening her with mediocrity. What she has gotten out of the deal is a knight who dares challenge Mab herself. I think that is, in its own way, worth it in Mab's book. If he was simply meekly obedient and dependant on Mab, he would be of much lesser use. Without the lesson that Uriel taught him, he would, for one, have been killed by Mother winter and unable to stop the battle at demonreach, or might well have chosen to become a plaything of Maeve's, going with with "I'm already a monster," line of reasoning, the meak defeatism he shows before Uriel gives him seven words. He would, in other words, not have been willfull enough to resist Mab's enemies.
