Hey there.
First off, we aren't allows to use stop losses here in Canada because of their overall dangers. We have to use stop limits. Stop losses trigger a market order at your stop price, whereas a stop limit triggers a limit order.
If you have a stop loss at say $5 on a stock and it goes to $5, your brokerage is going to sell your shares for whatever it can get. If the only open buy order is at $3.50, your shares will be sold at $3.50. A stop limit, you could set your limit to $4.90 which says sell at $5, but don't take less than $4.90.
The only way I use these, and it's in very rare conditions, is to protect profits. For example, right now I have a stop limit on my BTCC (Bitcoin) position considering its extensive volatility. I currently have no stop limits on my stocks.
That being said, if you want to lock in profits, stop limits are excellent. For some people, it helps them sleep at night knowing if the market bombs, their capital is protected via stop limits. So, I don't have any issues with investors using them. Lots say you "aren't an investor" if you use stop limits, but I think that's false.