Of course it's a matter of how fast you can react. The instant you feel the snow change you must brace with the extended tele position and get low. If you ski slower, you'll have another split second to sense what's going on. If the slope changes, well, you can see that coming. Get the idea of exposure to sun and wind.
Wind deposited snow is usually denser.
Sometimes you can see the texture change and know what to expect before you hit it. Sometimes you must just think about exposure angles to wind and sun to predict changes in the snow from turn to turn. Many times the backcountry snowpack is delicate and a careless shift in balance is all it takes to bog and faceplant. Say you teeter right and over-weight that ski to straighten. You were floating along just fine with your weight on two skis but with it all on one ski, even for an instant, that ski dives and so does your face.