It may get tiresome, but I dont have a problem with a coach asking to check with my partner, in fact, if I was a coach having this option, I'd do the same, the call just might get changed.
If I'm sure of my call, I just say no with an appropriate reply- no big deal.Its just a question being asked. It can become a prob if the coach asks on every call that didnt go his way, but I've never had that happen.

I didn't know that.......
 

Nat's apparently won a challenge in the top of the ninth against the Padres tonight, that maybe they shouldn't have.......

Padres runner attempts to steal second and is ruled safe. Replay shows him sliding over the bag, foot in the air, and being tagged out. Once seen by Nats on the replay, Mgr Matt Williams comes out of the dugout to "discuss" with the umpires. Unfortunately, the Nats pitcher was on the rubber and the Padres batter in the batter's box when this happened. Apparently, according to the new rule (kinda like the next snap in football) once the pitcher is on the rubber and batter in the box, you can't protest a call. The Padres Mgr knew the rule and argued.

But, after review, the umps ruled the runner out.

Interesting.