I use this excercise for technique, speed, and endurance training. It is an excercise based on triplets. When the following measure is played each hand will play four triplets or twelve notes consecutively. You can also interpret it as two sextuplets and two single hand triplets. The sextuplet is basically interleaving the triplets from both hands into a smooth single stroke pattern.

This excercise allows each hand to rest for two beats and then play for four beats. Doing this keeps you from tiring out so rapidly that you are unable to play using good form and technique. Playing without near perfect technique should almost never be done. If things start getting sloppy, slow the metronome down and start again until you can do it perfectly. You can easily customize this excercise by increasing the number of sextuplets and/or single hand triplets between the sextuplets. Increasing the number of single triplets played between the sextuplets will give each hand a longer resting time and allow you to focus on each hand individually.

As you get better try increasing the number of sextuplets played in a row. This will increase the level of physical difficulty but will increase your endurance in the long run.