How effective are Stop Limit Quotes

Im a novice, keep that in mind....

Testing out the waters with stop limit quotes. Invested in some tech stocks that people think will go higher, while others say they're primed for a crash/correction. Playing with small amounts of $, but using stop limit quotes to sell.

I monitor the 52 week highs and set the STOP to be 95% of that high, and the LIMIT to be 90% of that high. Is that 5% gap big enough to create a likelihood that the sale will execute, in case there happens to be quick drop in price? Is there an ideal gap between STOP and LIMIT?