A perfect example from my trading experience is UGAZ. On 10/1 thur afternoon, I set my stop loss at $5.55. It hit my stop loss and went back up after that (just one penny). What we do is try to protect our account in case it keeps dropping. You're rather losing 15% - 20% than 35% - 60%. When you lose 15 - 20%, it is so easy to get it back from these 3x etfs. When you lose more than 35%, it will be very hard to get it back.
Just my personal trading experience to share with you.