I found that they don’t work very well as support or resistance zones despite what candle lovers claim.
Gaps in an uptrend (rising windows) show underlying support 20% of the time in a bull market and 16% of the time in a bear market. In other words, when price drops and stumbles upon a gap that happened in a prior up trend, price will reverse at or within the gap 20% of the time.
For downtrends (falling windows), price hits overhead resistance setup by a prior gap 25% of the time in a bull market and 33% of the time in a bear market. That means price gaps lower (a downtrend) then curls around and tries to move higher, but runs into the gap and reverses.
Thomas Bulkowski. Gauging Gaps