If you feel like a trend will be long and strong it can be exponential to hold the 3x derivatives. The reset of choppy action is the enemy for longs of symbols like JNUG, etc....
See the "W e e k e n d R e p o r t" from 4/20 at this site,,,,http://rambus1.com/
This guy swears by holding tight, but he thinks you should be long DUST, and makes a pretty convincing case in the charts.