No, I don't, and here's why:
Challenges only occur on negative plays for the Packers. You wouldn't challenge a play if you just scored a long TD run or TD bomb from Rodgers.
McCarthy only seems to challenge the big plays - TD drops, TD catches for the other team (although that one he challenged in Baltimore shouldn't have been), fumbles, etc, like most coaches do. I don't think he's called any for rudimentary down and distance calls. Calling a timeout gives your offense or defense time to recuperate after having possibly given up a big play. That gives them time to reset and come back. If you win the challenge, that's even more of a momentum swing and confidence boost.
Whether or not in reality it breaks the flow of the offense or defense, I cannot say since I haven't paid particular attention to efficiency after a challenge. But hey, sometimes we wouldn't even have an offense to question if it weren't for some challenges (e.g. Grant's fumble).