Timing - Ken has explained that rather well, plus he mentioned a key method of relaxing the body, the breathing part, and of developing a routine for the body, especially a preshot routine. And Sawbones has stated many times that most timing problems can be traced to the Pushaway and the first step.
What you describe in the three examples doesnt necessarily seem like a timing issue to me. Hopefully someone will correct me if I am wrong on this, but timing to me is the act of having the footwork and armswing in sync with each other. Dropping the shoulder could be an indication that you are trying to put more on the shot than you should by trying to get 'under' the ball. Relax and dont try to muscle the armswing, let the weight of the ball carry your arm through the shot (key thought - pendulum). If you need more ballspeed, start by holding the ball higher, and for less ballspeed, hold the ball lower.
As for holding onto the ball too long, are you squeezing the ball? Are your thumb pitches and thumbhole size correct? Those two questions could be related.
Have your ball checked at your proshop. The thumb should feel 'snug', not too loose because that promotes unconscience squeezing in the backswing to hold onto the ball. Many bowlers use tape to keep the thumbhole feeling snug because for many, the thumb will swell or shrink daily and the insertion or removal of tape keeps the same feel for each day or shot. Other bowlers like myself, find that the Magic Carpets are a great help in getting a clean consistant release.
Also, are you keeping your kneebend the same and not straightening up on some of those lofted shots?
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I am the SGT Schultz of bowling.
"I know nothing!"