Developing dexterity and speed on steel pan depends to a large extent on correct sticking, correct wrist action and a proper approach to practicing fast passages of music.
Deciding which hand should play a particular note (sticking) is a personal choice. However, many difficulties, especially in faster pieces are as a result of incorrect or clumsy sticking. A few general rules are:
The best sticking occurs when right hand strokes and left hand strokes alternate i.e. strict alternation. If strict alternation is not possible, avoid playing more than three strokes in a row with the same hand. Avoid crossing hands
When learning a fast piece of music, start slowly and gradually increase the speed. Forcing speed only creates tension in the player.
Relax! If you have problems playing a fast passage of music, decrease the speed and practice until the slower tempo is comfortable. Only after you are perfectly comfortable playing at that tempo do you increase the speed. Using a metronome will help this process.
Remember to also make sure you are using the best sticking and strokes.