^ Thanks. I looked at the synopsis for that episode and came away with a very different interpretation than you apparently did. All that episode tells us is that, despite everything he's experienced, Harry isn't ready for the 'responsibilities of command'; that doesn't automatically equate to his character not having grown.
It does suggest that the overall level of development over the course of seven seasons was less than significant. Indeed, it was very much in line with many shows of the era--Beverly Hills 90210 and Friends, e.g.--in which the details of the characters lives changed, but the fundamental challenges that they faced remained the same. Nightengale, indeed, might have been an interesting episode in season 2, showing an eager newbie what growth will be expected of him. Instead, it highlights how little he had learned, and that the producers aren't content to show us how he evolves. All it leaves is the impression that Kim is hopelessly naive.