Your comment "...TO A FAIRLY LARGE EXTENT avys are predictable." is true. That predictability is why we take avy courses, a large pert of which are devoted to being ABLE to predict them. Things like weather history, hoar frost layers, slope compass aspect, fracture lines, etc. are all part of that "predictability". The snow study kit, inclinometer, shovel and saw for test pits are fully 1/2 the gear in terms of importance.
BUT... it's the UNpredictale part that means you'd better have good rescue equipment and the latest training. Shoveling out a victim takes the longest of any part of a rescue. Knowing HOW to shovel & paddle snow efficiently in a conveyor system of rotating lead shovelers is paramount. But having the correct shovels is also important, as, for ex., former owners of plastic bladed shovels discovered to their dismay.
It's all of a piece - good work at predicting avalanches and good work at rescuing victims when prediction fails horribly. And in all of this good equipment is often as vital as good knowledge.