I say they implement it through team fouls, each team can use 1 challenge per quarter. If its wrong it counts against team fouls and 30 second TO is deducted. If its right (call is overturned) then the team gets the chance to do it again in that quarter... This way the team is not just penalized with TO (which cancels because it will take that time to review the call anyway) but also with a team foul which could be costly down the stretch. The challenges would be used more carefully, but also, they wont be saved for late in the game. By spreading their use throughout the game, ref behavior can be scrutinized evenly through the game. What do y'all think?