I said Shir hashirim for my daughter 40 days in a row between chatzos and alos. This segula was suggested by one of my daughter’s teachers at the time. The phone call suggesting the shidduch for her beshert came on the 40 th day exactly. That was 10 years ago (She now has 4 kids). I have since done it for a number of other people with 100% success, including an aguna of 9 years (She got her get and remarried). I plan on starting for another daughter right after Tisha bav. (I once had a shyla about saying it on Tishabav and I feel it’s best to avoid it)