You beat my comment by 12 minutes. I'd add that the dev team should at least be part of the feedback loop. To bring up an example: I once worked on a project where the PMs and designers all came over from the Android project to bring up the iOS one. Many of the designs were specified to look and behave as the Android product did. A single button, if implemented according to their spec, would have meant developing a custom control + 200 lines of code-behind to mimic Android's behavior, where if we made some minor tweaks and used a native iOS-style control, it would be a one-liner (and by the way, would be more appealing users who expect iOS-like controls on their iPhones). Without this feedback, we'd probably still be building all those custom controls years later.