Not if the knowledge and perspective he can only gain from that walkabout is part and parcel of the training, I would think.
That would depend, I suppose, on what Harry actually gained by way of perspective. Ebenezar gave him the message about Mab and/or other beings not being able to compromise or change his Will, which was pretty well disproved by the Shadow's whisper. (Yes, it was cheating according to Uriel, but it still shoved Harry onto a path he may not have otherwise taken. And if the Fallen are capable of it, I'd be willing to bet that a lot of the higher-tier Old Ones can do it too.) Unless team UMO wanted Harry to consider things from a perspective in which he was nearly powerless to accomplish anything, thereby viewing those around him in a different light, the walkabout itself doesn't seem to have served a purpose beyond demonstrating that the Free Will clause is capable of being violated. And that doesn't really help turn Harry into a utility tool.
I don't, at this point, have enough handle on what the parasite is to have a strong feel for how it fits with this model. I can buy it being a resurgent Lash operating against the goals of team UMO; I could also, given the ending of GS, speculate that its presence in Harry is somehow essentialled for keeping his body usable while his soul is on walkabout.
Well... I can quibble about the resurgent Lash bit. There's a text precedent for the parasite having been placed before Harry picked up Lasciel's coin in DM, but the biggest issue I have with it (as it fits with your model) is that Lash is the one who tells Harry about his capabilities versus the Outsiders. If Lash is against one or more of team UMO's goals... why on earth would that shadow have bothered revealing that information to Harry?
The parasite being a necessary component for Dresden keeping his "life"... well, that's sort of ironic, given the result of its current state.