When you put it like that there is no reason not to throw it to Rico on every play.
Well, he'll have to show that he understands how to find the soft spot where he won't be undercut by a safety or linebacker. I keep going back to Jason Witten because he's such a great example of what a slower tight end needs to be. Witten does the subtle things to create separation, but he also is football wise, knowing where he needs to be to make himself a target for the quarterback. He reads the coverage and uses the flexibility of the route to find the soft spot.
These kind of practices favor the offense because there's usually a lot more straight-up matchups, no game-planning, etc. It's easier to post up a DB in those conditions, and frankly, if Rico didn't win those kind of matchups, there would be little hope for him. What's going to determine if he is worthy of getting on the field during the regular season is all those little things and whether he can block effectively. (Actually, if he can block effectively, he might get on the field even if he can't yet do all those little things.)