If you have master the art of shooting pool balls straight into the pockets it is important to remember other than keeping low and looking straight down the shaft of your cue that a good long mild stroke will always beat a shooter who is slamming balls around a table. The reason why is that rails are soft and are meant to compress. Plus if you shoot hard you have a higher rate of inaccurate shot. Most players who shoot harder, and harder are either 2 things. Inexperienced shooters, or they are trying to intimidate you or the crowd in some way.
Shooting into a pool ball into any pocket should be a very nice finesse calm shot with follow through. This way if you are a little off target when it hits the pocket corners it follows its Pattern and drops into the pocket. A great example of seeing this is when a shooter shoots too hard and it barley hits a corner it rattles back and forth in between a corner pocket, the reason why is when it hits the corner it compresses the rail which will change the complete angle of the shot itself. To prove this all you have to do is walk up to one of these pockets and press one the corner of the pocket, notice it sinks in. Now imagine you shooting a ball hard into that corner with the compression, you have now changed your angle completely and this is why pool palls rattle inside of pockets.
Pool is a complete game of finesse, watch the professionals if you notice none of them shoot hard or make any loud pocket noises. The reason why is they are taking their time with nice smooth long strokes and not focusing on power at all. So shooting hard does not force a pool balls or billard balls in, but a slower smooth shot can save you shot if you are a little off.