It need to be "good entertainment". And calling someone for 10 seconds on a free-throw isn't good entertainment.
Eh, how good of entertainment is a free throw?
The longer a free throw takes, the less entertaining it is. No? (Though it is kind of fun watching the crowd and players get upset).
Call it once, I bet he shoots it quicker the rest of the game, making the rest of the game more entertaining.
If it wasn't such an important Game 7 (and Harden/Durant weren't such good free throw shooters), I would love to see them sacrifice one on their end. Durant/Harden goes to the line, just hold it as long as possible until the refs call something. 20, 30, 45 seconds, however long it takes. Once they acknowledge the rule, they got to call it both ways, right, RIGHT? (ya right

) Kind of like how when a big man is upset he's not getting the ball, he'll camp out in the lane purposely getting a 3 second call so his teammates will be forced to acknowledge him.