It has always seemed to me that you needn't read back the new transponder code at all; ATC will see it in about three seconds...on the other hand, some acknowledgement is useful to pre-empt a second transmission of the same instruction.
I am in complete agreement regarding putting anything "on request"; drives me nuts as well, along with another favorite, "any chance of direct XYZ?"
Most of the wasted transmission time in the States could be eliminated in two ways: first, spend millions to install repeaters on ATC communications systems, so that everyone talking to that controller, regardless of frequency, can hear everyone else. Second, a two-step process for controllers to use with every transmission: first, don't move your lips before you push the button...second, after you push the button, move your lips. (This always gets an understanding chuckle from the controllers I remind personally when they are on my jumpseat.)
And none of you hit on my all-time favorite phrase that must be universally targeted for elimination: the incessant and ridiculous use, in PA announcements in the cabin and especially in the terminal, of the phrase "once again". Count them next time you fly. It seems this phrase must be part of every sentence used on a PA system. Now that drives me absolutely bonkers, particularly when combined with another favorite phrase..."once again, this will be the last and final boarding call"....
