I play a 45*, 50*, 56*, and 60*. If I had to drop one wedge I would get rid of the 50* since I use it the least and I would replace the 56* with a 54*. The 60* is by far my favorite wedge.
You will pry these from my dead cold hands when the time comes. The most useful clubs in my bag. Once I learned to control spin and trajectory coupled with a partial swing the 4th wedge was extra. The sand bunker shot is done with the 58* wedge 95% of the time adjusting the flare of face. Other wise a long bunker shot is simple with the 52*. As I have told sssmokin "sand is my friend"
I have tight hard turf here so bounce is keep to a minimum. 4* to 8* max. If I need more i just open the blade and swing flatter.