Bunker shots are indeed a bit unpredictable, although you can more or less estimate the roll when hitting from sand.
As the most of the bunkers are around the green I always punch, moving my aim to the place where the bounce will occur and then estimating the roll forward to try to stop it as close as possible to the hole.
Punch = Lets say I got a 30 yard sand shot with 40-50% to a flat green, with 3-4 mph wind, I hit approx 40 yards with full back spin and see the ball landing within 20-25 feet of the hole to hopefully roll somewhere close to the hole.
Like going out of rough, I always check the "landing" spot to see where the ball is going to roll, if the green is not flat.
Flop = There are several places where you can simply flop with full back spin even tho with 40-50% sand. hole 2, 4 at Beth, some holes at Pines for example, all is a matter of thinking that the ball lies "up right" in the bunker.
Problem with the flop from sand is that, if you miss the ding you may miss the shot badly.
IF the sand is only 15% you can add back spin to the shot and the ball will stop at landing, you need good wedges to do this tho.
Fairway sand trap?, I suppose we all know what to do.
Eric