In day to day operations yes. In the early days of T5 there was the very occasional tendency to bus from B and C but pretty much the only time that happens now is when Domestic comes into B or C, which is in itself very rare, or there is an airbridge mechanical failure.

Just for information, today the only A10 I can see at the moment is Zurich BA712, and nothing is showing for A4. My experience is that Canada and the smaller US locations are prime for A10 - Philadelphia and Calgary, but not always so, and it will change from day to day, they get B and C bridges from time to time. The other oft' bussed services are the late 767 services to Edinburgh and Glasgow from A4.